com.unity.netcode.gameobjects@1.3.1

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

Additional documentation and release notes are available at [Multiplayer Documentation](https://docs-multiplayer.unity3d.com).

## [1.3.1] - 2023-03-27

### Added

- Added detection and graceful handling of corrupt packets for additional safety. (#2419)

### Changed

- The UTP component UI has been updated to be more user-friendly for new users by adding a simple toggle to switch between local-only (127.0.0.1) and remote (0.0.0.0) binding modes, using the toggle "Allow Remote Connections" (#2408)
- Updated `UnityTransport` dependency on `com.unity.transport` to 1.3.3. (#2450)
- `NetworkShow()` of `NetworkObject`s are delayed until the end of the frame to ensure consistency of delta-driven variables like `NetworkList`.
- Dirty `NetworkObject` are reset at end-of-frame and not at serialization time.
- `NetworkHide()` of an object that was just `NetworkShow()`n produces a warning, as remote clients will _not_ get a spawn/despawn pair.
- Renamed the NetworkTransform.SetState parameter `shouldGhostsInterpolate` to `teleportDisabled` for better clarity of what that parameter does. (#2228)
- Network prefabs are now stored in a ScriptableObject that can be shared between NetworkManagers, and have been exposed for public access. By default, a Default Prefabs List is created that contains all NetworkObject prefabs in the project, and new NetworkManagers will default to using that unless that option is turned off in the Netcode for GameObjects settings. Existing NetworkManagers will maintain their existing lists, which can be migrated to the new format via a button in their inspector. (#2322)

### Fixed

- Fixed issue where changes to a layer's weight would not synchronize unless a state transition was occurring.(#2399)
- Fixed issue where `NetworkManager.LocalClientId` was returning the `NetworkTransport.ServerClientId` as opposed to the `NetworkManager.m_LocalClientId`. (#2398)
- Fixed issue where a dynamically spawned `NetworkObject` parented under an in-scene placed `NetworkObject` would have its `InScenePlaced` value changed to `true`. This would result in a soft synchronization error for late joining clients. (#2396)
- Fixed a UTP test that was failing when you install Unity Transport package 2.0.0 or newer. (#2347)
- Fixed issue where `NetcodeSettingsProvider` would throw an exception in Unity 2020.3.x versions. (#2345)
- Fixed server side issue where, depending upon component ordering, some NetworkBehaviour components might not have their OnNetworkDespawn method invoked if the client side disconnected. (#2323)
- Fixed a case where data corruption could occur when using UnityTransport when reaching a certain level of send throughput. (#2332)
- Fixed an issue in `UnityTransport` where an exception would be thrown if starting a Relay host/server on WebGL. This exception should only be thrown if using direct connections (where WebGL can't act as a host/server). (#2321)
- Fixed `NetworkAnimator` issue where it was not checking for `AnimatorStateTtansition.destinationStateMachine` and any possible sub-states defined within it. (#2309)
- Fixed `NetworkAnimator` issue where the host client was receiving the ClientRpc animation updates when the host was the owner.(#2309)
- Fixed `NetworkAnimator` issue with using pooled objects and when specific properties are cleaned during despawn and destroy.(#2309)
- Fixed issue where `NetworkAnimator` was checking for animation changes when the associated `NetworkObject` was not spawned.(#2309)
- Corrected an issue with the documentation for BufferSerializer (#2401)

CHANGELOG.md

@@ -6,6 +6,38 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 Additional documentation and release notes are available at [Multiplayer Documentation](https://docs-multiplayer.unity3d.com).
 
+## [1.3.1] - 2023-03-27
+
+### Added
+
+- Added detection and graceful handling of corrupt packets for additional safety. (#2419)
+
+### Changed
+
+- The UTP component UI has been updated to be more user-friendly for new users by adding a simple toggle to switch between local-only (127.0.0.1) and remote (0.0.0.0) binding modes, using the toggle "Allow Remote Connections" (#2408)
+- Updated `UnityTransport` dependency on `com.unity.transport` to 1.3.3. (#2450)
+- `NetworkShow()` of `NetworkObject`s are delayed until the end of the frame to ensure consistency of delta-driven variables like `NetworkList`.
+- Dirty `NetworkObject` are reset at end-of-frame and not at serialization time.
+- `NetworkHide()` of an object that was just `NetworkShow()`n produces a warning, as remote clients will _not_ get a spawn/despawn pair.
+- Renamed the NetworkTransform.SetState parameter `shouldGhostsInterpolate` to `teleportDisabled` for better clarity of what that parameter does. (#2228)
+- Network prefabs are now stored in a ScriptableObject that can be shared between NetworkManagers, and have been exposed for public access. By default, a Default Prefabs List is created that contains all NetworkObject prefabs in the project, and new NetworkManagers will default to using that unless that option is turned off in the Netcode for GameObjects settings. Existing NetworkManagers will maintain their existing lists, which can be migrated to the new format via a button in their inspector. (#2322)
+
+### Fixed
+
+- Fixed issue where changes to a layer's weight would not synchronize unless a state transition was occurring.(#2399)
+- Fixed issue where `NetworkManager.LocalClientId` was returning the `NetworkTransport.ServerClientId` as opposed to the `NetworkManager.m_LocalClientId`. (#2398)
+- Fixed issue where a dynamically spawned `NetworkObject` parented under an in-scene placed `NetworkObject` would have its `InScenePlaced` value changed to `true`. This would result in a soft synchronization error for late joining clients. (#2396)
+- Fixed a UTP test that was failing when you install Unity Transport package 2.0.0 or newer. (#2347)
+- Fixed issue where `NetcodeSettingsProvider` would throw an exception in Unity 2020.3.x versions. (#2345)
+- Fixed server side issue where, depending upon component ordering, some NetworkBehaviour components might not have their OnNetworkDespawn method invoked if the client side disconnected. (#2323)
+- Fixed a case where data corruption could occur when using UnityTransport when reaching a certain level of send throughput. (#2332)
+- Fixed an issue in `UnityTransport` where an exception would be thrown if starting a Relay host/server on WebGL. This exception should only be thrown if using direct connections (where WebGL can't act as a host/server). (#2321)
+- Fixed `NetworkAnimator` issue where it was not checking for `AnimatorStateTtansition.destinationStateMachine` and any possible sub-states defined within it. (#2309)
+- Fixed `NetworkAnimator` issue where the host client was receiving the ClientRpc animation updates when the host was the owner.(#2309)
+- Fixed `NetworkAnimator` issue with using pooled objects and when specific properties are cleaned during despawn and destroy.(#2309)
+- Fixed issue where `NetworkAnimator` was checking for animation changes when the associated `NetworkObject` was not spawned.(#2309)
+- Corrected an issue with the documentation for BufferSerializer (#2401)
+
 ## [1.2.0] - 2022-11-21
 
 ### Added
@@ -22,7 +54,7 @@ Additional documentation and release notes are available at [Multiplayer Documen
 - Optimized bandwidth usage by encoding most integer fields using variable-length encoding. (#2276)
 
 ### Fixed
-
+- Fixed `IsSpawnedObjectsPendingInDontDestroyOnLoad` is only set to true when loading a scene using `LoadSceneMode.Singleonly`. (#2330)
 - Fixed issue where `NetworkTransform` components nested under a parent with a `NetworkObject` component  (i.e. network prefab) would not have their associated `GameObject`'s transform synchronized. (#2298)
 - Fixed issue where `NetworkObject`s that failed to instantiate could cause the entire synchronization pipeline to be disrupted/halted for a connecting client. (#2298)
 - Fixed issue where in-scene placed `NetworkObject`s nested under a `GameObject` would be added to the orphaned children list causing continual console warning log messages. (#2298)

Components/AssemblyInfo.cs

@@ -1,10 +1,15 @@
 using System.Runtime.CompilerServices;
 
 #if UNITY_EDITOR
-[assembly: InternalsVisibleTo("Unity.Netcode.EditorTests")]
-[assembly: InternalsVisibleTo("Unity.Netcode.Editor.CodeGen")]
 [assembly: InternalsVisibleTo("Unity.Netcode.Editor")]
-[assembly: InternalsVisibleTo("TestProject.EditorTests")]
-[assembly: InternalsVisibleTo("TestProject.RuntimeTests")]
-#endif
+[assembly: InternalsVisibleTo("Unity.Netcode.Editor.CodeGen")]
+#endif // UNITY_EDITOR
+
+#if UNITY_INCLUDE_TESTS
 [assembly: InternalsVisibleTo("Unity.Netcode.RuntimeTests")]
+[assembly: InternalsVisibleTo("TestProject.RuntimeTests")]
+#if UNITY_EDITOR
+[assembly: InternalsVisibleTo("Unity.Netcode.EditorTests")]
+[assembly: InternalsVisibleTo("TestProject.EditorTests")]
+#endif // UNITY_EDITOR
+#endif // UNITY_INCLUDE_TESTS

Components/NetworkAnimator.cs

@@ -23,12 +23,6 @@ namespace Unity.Netcode.Components
         /// </summary>
         private void FlushMessages()
         {
-            foreach (var clientId in m_ClientsToSynchronize)
-            {
-                m_NetworkAnimator.ServerSynchronizeNewPlayer(clientId);
-            }
-            m_ClientsToSynchronize.Clear();
-
             foreach (var sendEntry in m_SendParameterUpdates)
             {
                 m_NetworkAnimator.SendParametersUpdateClientRpc(sendEntry.ParametersUpdateMessage, sendEntry.ClientRpcParams);
@@ -64,9 +58,10 @@ namespace Unity.Netcode.Components
                         }
 
                         // Everyone applies any parameters updated
-                        foreach (var parameterUpdate in m_ProcessParameterUpdates)
+                        for (int i = 0; i < m_ProcessParameterUpdates.Count; i++)
                         {
-                            m_NetworkAnimator.UpdateParameters(parameterUpdate);
+                            var parameterUpdate = m_ProcessParameterUpdates[i];
+                            m_NetworkAnimator.UpdateParameters(ref parameterUpdate);
                         }
                         m_ProcessParameterUpdates.Clear();
 
@@ -80,20 +75,6 @@ namespace Unity.Netcode.Components
             }
         }
 
-        /// <summary>
-        /// Clients that need to be synchronized to the relative Animator
-        /// </summary>
-        private List<ulong> m_ClientsToSynchronize = new List<ulong>();
-
-        /// <summary>
-        /// When a new client is connected, they are added to the
-        /// m_ClientsToSynchronize list.
-        /// </summary>
-        internal void SynchronizeClient(ulong clientId)
-        {
-            m_ClientsToSynchronize.Add(clientId);
-        }
-
         /// <summary>
         /// A pending outgoing Animation update for (n) clients
         /// </summary>
@@ -157,13 +138,6 @@ namespace Unity.Netcode.Components
             m_SendTriggerUpdates.Add(new TriggerUpdate() { AnimationTriggerMessage = animationTriggerMessage, SendToServer = true });
         }
 
-        private Queue<NetworkAnimator.AnimationMessage> m_AnimationMessageQueue = new Queue<NetworkAnimator.AnimationMessage>();
-
-        internal void AddAnimationMessageToProcessQueue(NetworkAnimator.AnimationMessage message)
-        {
-            m_AnimationMessageQueue.Enqueue(message);
-        }
-
         internal void DeregisterUpdate()
         {
             NetworkUpdateLoop.UnregisterNetworkUpdate(this, NetworkUpdateStage.PreUpdate);
@@ -226,13 +200,82 @@ namespace Unity.Netcode.Components
             }
         }
 
+#if UNITY_EDITOR
+        private void ParseStateMachineStates(int layerIndex, ref AnimatorController animatorController, ref AnimatorStateMachine stateMachine)
+        {
+            for (int y = 0; y < stateMachine.states.Length; y++)
+            {
+                var animatorState = stateMachine.states[y].state;
+                for (int z = 0; z < animatorState.transitions.Length; z++)
+                {
+                    var transition = animatorState.transitions[z];
+                    if (transition.conditions.Length == 0 && transition.isExit)
+                    {
+                        // We don't need to worry about exit transitions with no conditions
+                        continue;
+                    }
+
+                    foreach (var condition in transition.conditions)
+                    {
+                        var parameterName = condition.parameter;
+
+                        var parameters = animatorController.parameters;
+                        // Find the associated parameter for the condition
+                        foreach (var parameter in parameters)
+                        {
+                            // Only process the associated parameter(s)
+                            if (parameter.name != parameterName)
+                            {
+                                continue;
+                            }
+
+                            switch (parameter.type)
+                            {
+                                case AnimatorControllerParameterType.Trigger:
+                                    {
+
+                                        if (transition.destinationStateMachine != null)
+                                        {
+                                            var destinationStateMachine = transition.destinationStateMachine;
+                                            ParseStateMachineStates(layerIndex, ref animatorController, ref destinationStateMachine);
+                                        }
+                                        else if (transition.destinationState != null)
+                                        {
+                                            var transitionInfo = new TransitionStateinfo()
+                                            {
+                                                Layer = layerIndex,
+                                                OriginatingState = animatorState.nameHash,
+                                                DestinationState = transition.destinationState.nameHash,
+                                                TransitionDuration = transition.duration,
+                                                TriggerNameHash = parameter.nameHash,
+                                                TransitionIndex = z
+                                            };
+                                            TransitionStateInfoList.Add(transitionInfo);
+                                        }
+                                        else
+                                        {
+                                            Debug.LogError($"[{name}][Conditional Transition for {animatorState.name}] Conditional triggered transition has neither a DestinationState nor a DestinationStateMachine! This transition is not likely to synchronize properly. " +
+                                                $"Please file a GitHub issue about this error with details about your Animator's setup.");
+                                        }
+                                        break;
+                                    }
+                                default:
+                                    break;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+#endif
+
         /// <summary>
         /// Creates the TransitionStateInfoList table
         /// </summary>
         private void BuildTransitionStateInfoList()
         {
 #if UNITY_EDITOR
-            if (UnityEditor.EditorApplication.isUpdating)
+            if (UnityEditor.EditorApplication.isUpdating || UnityEditor.EditorApplication.isPlayingOrWillChangePlaymode)
             {
                 return;
             }
@@ -245,54 +288,8 @@ namespace Unity.Netcode.Components
 
             for (int x = 0; x < animatorController.layers.Length; x++)
             {
-                var layer = animatorController.layers[x];
-
-                for (int y = 0; y < layer.stateMachine.states.Length; y++)
-                {
-                    var animatorState = layer.stateMachine.states[y].state;
-                    var transitions = layer.stateMachine.GetStateMachineTransitions(layer.stateMachine);
-                    for (int z = 0; z < animatorState.transitions.Length; z++)
-                    {
-                        var transition = animatorState.transitions[z];
-                        if (transition.conditions.Length == 0 && transition.isExit)
-                        {
-                            // We don't need to worry about exit transitions with no conditions
-                            continue;
-                        }
-
-                        foreach (var condition in transition.conditions)
-                        {
-                            var parameterName = condition.parameter;
-                            var parameters = animatorController.parameters;
-                            foreach (var parameter in parameters)
-                            {
-                                switch (parameter.type)
-                                {
-                                    case AnimatorControllerParameterType.Trigger:
-                                        {
-                                            // Match the condition with an existing trigger
-                                            if (parameterName == parameter.name)
-                                            {
-                                                var transitionInfo = new TransitionStateinfo()
-                                                {
-                                                    Layer = x,
-                                                    OriginatingState = animatorState.nameHash,
-                                                    DestinationState = transition.destinationState.nameHash,
-                                                    TransitionDuration = transition.duration,
-                                                    TriggerNameHash = parameter.nameHash,
-                                                    TransitionIndex = z
-                                                };
-                                                TransitionStateInfoList.Add(transitionInfo);
-                                            }
-                                            break;
-                                        }
-                                    default:
-                                        break;
-                                }
-                            }
-                        }
-                    }
-                }
+                var stateMachine = animatorController.layers[x].stateMachine;
+                ParseStateMachineStates(x, ref animatorController, ref stateMachine);
             }
 #endif
         }
@@ -488,8 +485,17 @@ namespace Unity.Netcode.Components
         private int[] m_AnimationHash;
         private float[] m_LayerWeights;
         private static byte[] s_EmptyArray = new byte[] { };
+        private List<int> m_ParametersToUpdate;
+        private List<ulong> m_ClientSendList;
+        private ClientRpcParams m_ClientRpcParams;
+        private AnimationMessage m_AnimationMessage;
         private NetworkAnimatorStateChangeHandler m_NetworkAnimatorStateChangeHandler;
 
+        /// <summary>
+        /// Used for integration test purposes
+        /// </summary>
+        internal List<AnimatorStateInfo> SynchronizationStateInfo;
+
         private unsafe struct AnimatorParamCache
         {
             internal int Hash;
@@ -519,75 +525,44 @@ namespace Unity.Netcode.Components
             }
         }
 
-        private void Cleanup()
+        /// <summary>
+        /// Only things instantiated/created within OnNetworkSpawn should be
+        /// cleaned up here.
+        /// </summary>
+        private void SpawnCleanup()
         {
             if (m_NetworkAnimatorStateChangeHandler != null)
             {
                 m_NetworkAnimatorStateChangeHandler.DeregisterUpdate();
                 m_NetworkAnimatorStateChangeHandler = null;
             }
+        }
 
-            if (m_CachedNetworkManager != null)
-            {
-                m_CachedNetworkManager.OnClientConnectedCallback -= OnClientConnectedCallback;
-            }
+        public override void OnDestroy()
+        {
+            SpawnCleanup();
 
             if (m_CachedAnimatorParameters != null && m_CachedAnimatorParameters.IsCreated)
             {
                 m_CachedAnimatorParameters.Dispose();
             }
+
             if (m_ParameterWriter.IsInitialized)
             {
                 m_ParameterWriter.Dispose();
             }
-        }
-
-        public override void OnDestroy()
-        {
-            Cleanup();
             base.OnDestroy();
         }
 
-        private List<int> m_ParametersToUpdate;
-        private List<ulong> m_ClientSendList;
-        private ClientRpcParams m_ClientRpcParams;
-        private AnimationMessage m_AnimationMessage;
-
-        /// <summary>
-        /// Used for integration test to validate that the
-        /// AnimationMessage.AnimationStates remains the same
-        /// size as the layer count.
-        /// </summary>
-        internal AnimationMessage GetAnimationMessage()
-        {
-            return m_AnimationMessage;
-        }
-
-        // Only used in Cleanup
-        private NetworkManager m_CachedNetworkManager;
-
-        /// <inheritdoc/>
-        public override void OnNetworkSpawn()
+        private void Awake()
         {
             int layers = m_Animator.layerCount;
-
             // Initializing the below arrays for everyone handles an issue
             // when running in owner authoritative mode and the owner changes.
             m_TransitionHash = new int[layers];
             m_AnimationHash = new int[layers];
             m_LayerWeights = new float[layers];
 
-            if (IsServer)
-            {
-                m_ClientSendList = new List<ulong>(128);
-                m_ClientRpcParams = new ClientRpcParams();
-                m_ClientRpcParams.Send = new ClientRpcSendParams();
-                m_ClientRpcParams.Send.TargetClientIds = m_ClientSendList;
-
-                // Cache the NetworkManager instance to remove the OnClientConnectedCallback subscription
-                m_CachedNetworkManager = NetworkManager;
-                NetworkManager.OnClientConnectedCallback += OnClientConnectedCallback;
-            }
             // We initialize the m_AnimationMessage for all instances in the event that
             // ownership or authority changes during runtime.
             m_AnimationMessage = new AnimationMessage();
@@ -612,6 +587,7 @@ namespace Unity.Netcode.Components
             var parameters = m_Animator.parameters;
             m_CachedAnimatorParameters = new NativeArray<AnimatorParamCache>(parameters.Length, Allocator.Persistent);
             m_ParametersToUpdate = new List<int>(parameters.Length);
+
             for (var i = 0; i < parameters.Length; i++)
             {
                 var parameter = parameters[i];
@@ -652,110 +628,163 @@ namespace Unity.Netcode.Components
 
                 m_CachedAnimatorParameters[i] = cacheParam;
             }
+        }
+
+        /// <summary>
+        /// Used for integration test to validate that the
+        /// AnimationMessage.AnimationStates remains the same
+        /// size as the layer count.
+        /// </summary>
+        internal AnimationMessage GetAnimationMessage()
+        {
+            return m_AnimationMessage;
+        }
+
+        /// <inheritdoc/>
+        public override void OnNetworkSpawn()
+        {
+            if (IsServer)
+            {
+                m_ClientSendList = new List<ulong>(128);
+                m_ClientRpcParams = new ClientRpcParams();
+                m_ClientRpcParams.Send = new ClientRpcSendParams();
+                m_ClientRpcParams.Send.TargetClientIds = m_ClientSendList;
+            }
+
+            // Create a handler for state changes
             m_NetworkAnimatorStateChangeHandler = new NetworkAnimatorStateChangeHandler(this);
         }
 
         /// <inheritdoc/>
         public override void OnNetworkDespawn()
         {
-            Cleanup();
+            SpawnCleanup();
         }
 
         /// <summary>
-        /// Synchronizes newly joined players
+        /// Wries all parameter and state information needed to initially synchronize a client
         /// </summary>
-        internal void ServerSynchronizeNewPlayer(ulong playerId)
+        private void WriteSynchronizationData<T>(ref BufferSerializer<T> serializer) where T : IReaderWriter
         {
-            m_ClientSendList.Clear();
-            m_ClientSendList.Add(playerId);
-            m_ClientRpcParams.Send.TargetClientIds = m_ClientSendList;
-            // With synchronization we send all parameters
-            m_ParametersToUpdate.Clear();
-            for (int i = 0; i < m_CachedAnimatorParameters.Length; i++)
+            // Parameter synchronization
             {
-                m_ParametersToUpdate.Add(i);
-            }
-            SendParametersUpdate(m_ClientRpcParams);
-
-            // Reset the dirty count before synchronizing the newly connected client with all layers
-            m_AnimationMessage.IsDirtyCount = 0;
-
-            for (int layer = 0; layer < m_Animator.layerCount; layer++)
-            {
-                AnimatorStateInfo st = m_Animator.GetCurrentAnimatorStateInfo(layer);
-                var stateHash = st.fullPathHash;
-                var normalizedTime = st.normalizedTime;
-                var isInTransition = m_Animator.IsInTransition(layer);
-
-                // Grab one of the available AnimationState entries so we can fill it with the current
-                // layer's animation state.
-                var animationState = m_AnimationMessage.AnimationStates[layer];
-
-                // Synchronizing transitions with trigger conditions for late joining clients is now
-                // handled by cross fading between the late joining client's current layer's AnimationState
-                // and the transition's destination AnimationState.
-                if (isInTransition)
+                // We include all parameters for the initial synchronization
+                m_ParametersToUpdate.Clear();
+                for (int i = 0; i < m_CachedAnimatorParameters.Length; i++)
                 {
-                    var tt = m_Animator.GetAnimatorTransitionInfo(layer);
-                    var nextState = m_Animator.GetNextAnimatorStateInfo(layer);
+                    m_ParametersToUpdate.Add(i);
+                }
+                // Write, apply, and serialize
+                WriteParameters(ref m_ParameterWriter);
+                var parametersMessage = new ParametersUpdateMessage
+                {
+                    Parameters = m_ParameterWriter.ToArray()
+                };
+                serializer.SerializeValue(ref parametersMessage);
+            }
 
-                    if (nextState.length > 0)
-                    {
-                        var nextStateTotalSpeed = nextState.speed * nextState.speedMultiplier;
-                        var nextStateAdjustedLength = nextState.length * nextStateTotalSpeed;
-                        // TODO: We need to get the transition curve for the target state as well as some
-                        // reasonable RTT estimate in order to get a more precise normalized synchronization time
-                        var transitionTime = Mathf.Min(tt.duration, tt.duration * tt.normalizedTime) * 0.5f;
-                        normalizedTime = Mathf.Min(1.0f, transitionTime > 0.0f ? transitionTime / nextStateAdjustedLength : 0.0f);
-                    }
-                    else
-                    {
-                        normalizedTime = 0.0f;
-                    }
-                    stateHash = nextState.fullPathHash;
+            // Animation state synchronization
+            {
+                // Reset the dirty count before synchronizing the newly connected client with all layers
+                m_AnimationMessage.IsDirtyCount = 0;
 
-                    // Use the destination state to transition info lookup table to see if this is a transition we can
-                    // synchronize using cross fading
-                    if (m_DestinationStateToTransitioninfo.ContainsKey(layer))
+                for (int layer = 0; layer < m_Animator.layerCount; layer++)
+                {
+                    var synchronizationStateInfo = m_Animator.GetCurrentAnimatorStateInfo(layer);
+                    if (SynchronizationStateInfo != null)
                     {
-                        if (m_DestinationStateToTransitioninfo[layer].ContainsKey(nextState.shortNameHash))
+                        SynchronizationStateInfo.Add(synchronizationStateInfo);
+                    }
+                    var stateHash = synchronizationStateInfo.fullPathHash;
+                    var normalizedTime = synchronizationStateInfo.normalizedTime;
+                    var isInTransition = m_Animator.IsInTransition(layer);
+
+                    // Grab one of the available AnimationState entries so we can fill it with the current
+                    // layer's animation state.
+                    var animationState = m_AnimationMessage.AnimationStates[layer];
+
+                    // Synchronizing transitions with trigger conditions for late joining clients is now
+                    // handled by cross fading between the late joining client's current layer's AnimationState
+                    // and the transition's destination AnimationState.
+                    if (isInTransition)
+                    {
+                        var tt = m_Animator.GetAnimatorTransitionInfo(layer);
+                        var nextState = m_Animator.GetNextAnimatorStateInfo(layer);
+
+                        if (nextState.length > 0)
                         {
-                            var destinationInfo = m_DestinationStateToTransitioninfo[layer][nextState.shortNameHash];
-                            stateHash = destinationInfo.OriginatingState;
-                            // Set the destination state to cross fade to from the originating state
-                            animationState.DestinationStateHash = destinationInfo.DestinationState;
+                            var nextStateTotalSpeed = nextState.speed * nextState.speedMultiplier;
+                            var nextStateAdjustedLength = nextState.length * nextStateTotalSpeed;
+                            // TODO: We need to get the transition curve for the target state as well as some
+                            // reasonable RTT estimate in order to get a more precise normalized synchronization time
+                            var transitionTime = Mathf.Min(tt.duration, tt.duration * tt.normalizedTime) * 0.5f;
+                            normalizedTime = Mathf.Min(1.0f, transitionTime > 0.0f ? transitionTime / nextStateAdjustedLength : 0.0f);
+                        }
+                        else
+                        {
+                            normalizedTime = 0.0f;
+                        }
+                        stateHash = nextState.fullPathHash;
+
+                        // Use the destination state to transition info lookup table to see if this is a transition we can
+                        // synchronize using cross fading
+                        if (m_DestinationStateToTransitioninfo.ContainsKey(layer))
+                        {
+                            if (m_DestinationStateToTransitioninfo[layer].ContainsKey(nextState.shortNameHash))
+                            {
+                                var destinationInfo = m_DestinationStateToTransitioninfo[layer][nextState.shortNameHash];
+                                stateHash = destinationInfo.OriginatingState;
+                                // Set the destination state to cross fade to from the originating state
+                                animationState.DestinationStateHash = destinationInfo.DestinationState;
+                            }
                         }
                     }
+
+                    animationState.Transition = isInTransition;        // The only time this could be set to true
+                    animationState.StateHash = stateHash;              // When a transition, this is the originating/starting state
+                    animationState.NormalizedTime = normalizedTime;
+                    animationState.Layer = layer;
+                    animationState.Weight = m_LayerWeights[layer];
+
+                    // Apply the changes
+                    m_AnimationMessage.AnimationStates[layer] = animationState;
                 }
-
-                animationState.Transition = isInTransition;        // The only time this could be set to true
-                animationState.StateHash = stateHash;              // When a transition, this is the originating/starting state
-                animationState.NormalizedTime = normalizedTime;
-                animationState.Layer = layer;
-                animationState.Weight = m_LayerWeights[layer];
-
-                // Apply the changes
-                m_AnimationMessage.AnimationStates[layer] = animationState;
+                // Send all animation states
+                m_AnimationMessage.IsDirtyCount = m_Animator.layerCount;
+                m_AnimationMessage.NetworkSerialize(serializer);
             }
-            // Send all animation states
-            m_AnimationMessage.IsDirtyCount = m_Animator.layerCount;
-            SendAnimStateClientRpc(m_AnimationMessage, m_ClientRpcParams);
         }
 
         /// <summary>
-        /// Required for the server to synchronize newly joining players
+        /// Used to synchronize newly joined clients
         /// </summary>
-        private void OnClientConnectedCallback(ulong playerId)
+        protected override void OnSynchronize<T>(ref BufferSerializer<T> serializer)
         {
-            m_NetworkAnimatorStateChangeHandler.SynchronizeClient(playerId);
+            if (serializer.IsWriter)
+            {
+                WriteSynchronizationData(ref serializer);
+            }
+            else
+            {
+                var parameters = new ParametersUpdateMessage();
+                var animationStates = new AnimationMessage();
+                serializer.SerializeValue(ref parameters);
+                UpdateParameters(ref parameters);
+                serializer.SerializeValue(ref animationStates);
+                HandleAnimStateUpdate(ref animationStates);
+            }
         }
 
         /// <summary>
         /// Checks for changes in both Animator parameters and state.
         /// </summary>
+        /// <remarks>
+        /// This is only invoked by clients that are the owner when not in server authoritative mode
+        /// or by the server itself when in server authoritative mode.
+        /// </remarks>
         internal void CheckForAnimatorChanges()
         {
-            if (!IsOwner && !IsServerAuthoritative() || IsServerAuthoritative() && !IsServer)
+            if (!IsSpawned || (!IsOwner && !IsServerAuthoritative()) || (IsServerAuthoritative() && !IsServer))
             {
                 return;
             }
@@ -817,6 +846,11 @@ namespace Unity.Netcode.Components
                 }
                 else
                 {
+                    // Just notify all remote clients and not the local server
+                    m_ClientSendList.Clear();
+                    m_ClientSendList.AddRange(NetworkManager.ConnectedClientsIds);
+                    m_ClientSendList.Remove(NetworkManager.LocalClientId);
+                    m_ClientRpcParams.Send.TargetClientIds = m_ClientSendList;
                     SendAnimStateClientRpc(m_AnimationMessage);
                 }
             }
@@ -824,10 +858,7 @@ namespace Unity.Netcode.Components
 
         private void SendParametersUpdate(ClientRpcParams clientRpcParams = default, bool sendDirect = false)
         {
-            m_ParameterWriter.Seek(0);
-            m_ParameterWriter.Truncate();
-
-            WriteParameters(m_ParameterWriter, sendDirect);
+            WriteParameters(ref m_ParameterWriter);
 
             var parametersMessage = new ParametersUpdateMessage
             {
@@ -961,8 +992,10 @@ namespace Unity.Netcode.Components
         /// This uses the m_ParametersToUpdate list to write out only
         /// the parameters that have changed
         /// </summary>
-        private unsafe void WriteParameters(FastBufferWriter writer, bool sendCacheState)
+        private unsafe void WriteParameters(ref FastBufferWriter writer)
         {
+            writer.Seek(0);
+            writer.Truncate();
             // Write how many parameter entries we are going to write
             BytePacker.WriteValuePacked(writer, (uint)m_ParametersToUpdate.Count);
             foreach (var parameterIndex in m_ParametersToUpdate)
@@ -1049,7 +1082,7 @@ namespace Unity.Netcode.Components
         /// <summary>
         /// Applies the ParametersUpdateMessage state to the Animator
         /// </summary>
-        internal unsafe void UpdateParameters(ParametersUpdateMessage parametersUpdate)
+        internal unsafe void UpdateParameters(ref ParametersUpdateMessage parametersUpdate)
         {
             if (parametersUpdate.Parameters != null && parametersUpdate.Parameters.Length != 0)
             {
@@ -1067,6 +1100,16 @@ namespace Unity.Netcode.Components
         /// </summary>
         internal void UpdateAnimationState(AnimationState animationState)
         {
+            // Handle updating layer weights first.
+            if (animationState.Layer < m_LayerWeights.Length)
+            {
+                if (m_LayerWeights[animationState.Layer] != animationState.Weight)
+                {
+                    m_Animator.SetLayerWeight(animationState.Layer, animationState.Weight);
+                }
+            }
+
+            // If there is no state transition then return
             if (animationState.StateHash == 0)
             {
                 return;
@@ -1114,7 +1157,6 @@ namespace Unity.Netcode.Components
                     m_Animator.Play(animationState.StateHash, animationState.Layer, animationState.NormalizedTime);
                 }
             }
-            m_Animator.SetLayerWeight(animationState.Layer, animationState.Weight);
         }
 
         /// <summary>
@@ -1134,7 +1176,7 @@ namespace Unity.Netcode.Components
                 {
                     return;
                 }
-                UpdateParameters(parametersUpdate);
+                UpdateParameters(ref parametersUpdate);
                 if (NetworkManager.ConnectedClientsIds.Count > (IsHost ? 2 : 1))
                 {
                     m_ClientSendList.Clear();
@@ -1183,7 +1225,6 @@ namespace Unity.Netcode.Components
                     UpdateAnimationState(animationState);
                 }
 
-                m_NetworkAnimatorStateChangeHandler.AddAnimationMessageToProcessQueue(animationMessage);
                 if (NetworkManager.ConnectedClientsIds.Count > (IsHost ? 2 : 1))
                 {
                     m_ClientSendList.Clear();
@@ -1196,6 +1237,18 @@ namespace Unity.Netcode.Components
             }
         }
 
+        internal void HandleAnimStateUpdate(ref AnimationMessage animationMessage)
+        {
+            var isServerAuthoritative = IsServerAuthoritative();
+            if (!isServerAuthoritative && !IsOwner || isServerAuthoritative)
+            {
+                foreach (var animationState in animationMessage.AnimationStates)
+                {
+                    UpdateAnimationState(animationState);
+                }
+            }
+        }
+
         /// <summary>
         /// Internally-called RPC client receiving function to update some animation state on a client
         /// </summary>
@@ -1211,15 +1264,7 @@ namespace Unity.Netcode.Components
                 }
                 return;
             }
-
-            var isServerAuthoritative = IsServerAuthoritative();
-            if (!isServerAuthoritative && !IsOwner || isServerAuthoritative)
-            {
-                foreach (var animationState in animationMessage.AnimationStates)
-                {
-                    UpdateAnimationState(animationState);
-                }
-            }
+            HandleAnimStateUpdate(ref animationMessage);
         }
 
         /// <summary>
@@ -1319,7 +1364,7 @@ namespace Unity.Netcode.Components
                     m_NetworkAnimatorStateChangeHandler.QueueTriggerUpdateToClient(animTriggerMessage);
                     if (!IsHost)
                     {
-                        InternalSetTrigger(hash);
+                        InternalSetTrigger(hash, setTrigger);
                     }
                 }
                 else
@@ -1328,7 +1373,7 @@ namespace Unity.Netcode.Components
                     m_NetworkAnimatorStateChangeHandler.QueueTriggerUpdateToServer(animTriggerMessage);
                     if (!IsServerAuthoritative())
                     {
-                        InternalSetTrigger(hash);
+                        InternalSetTrigger(hash, setTrigger);
                     }
                 }
             }

Components/NetworkTransform.cs

@@ -1092,10 +1092,9 @@ namespace Unity.Netcode.Components
         /// <param name="posIn"></param> new position to move to.  Can be null
         /// <param name="rotIn"></param> new rotation to rotate to.  Can be null
         /// <param name="scaleIn">new scale to scale to. Can be null</param>
-        /// <param name="shouldGhostsInterpolate">Should other clients interpolate this change or not. True by default</param>
-        /// new scale to scale to.  Can be null
+        /// <param name="teleportDisabled">When true (the default) the <see cref="NetworkObject"/> will not be teleported and, if enabled, will interpolate. When false the <see cref="NetworkObject"/> will teleport/apply the parameters provided immediately.</param>
         /// <exception cref="Exception"></exception>
-        public void SetState(Vector3? posIn = null, Quaternion? rotIn = null, Vector3? scaleIn = null, bool shouldGhostsInterpolate = true)
+        public void SetState(Vector3? posIn = null, Quaternion? rotIn = null, Vector3? scaleIn = null, bool teleportDisabled = true)
         {
             if (!IsSpawned)
             {
@@ -1119,16 +1118,16 @@ namespace Unity.Netcode.Components
                 {
                     m_ClientIds[0] = OwnerClientId;
                     m_ClientRpcParams.Send.TargetClientIds = m_ClientIds;
-                    SetStateClientRpc(pos, rot, scale, !shouldGhostsInterpolate, m_ClientRpcParams);
+                    SetStateClientRpc(pos, rot, scale, !teleportDisabled, m_ClientRpcParams);
                 }
                 else // Preserving the ability for server authoritative mode to accept state changes from owner
                 {
-                    SetStateServerRpc(pos, rot, scale, !shouldGhostsInterpolate);
+                    SetStateServerRpc(pos, rot, scale, !teleportDisabled);
                 }
                 return;
             }
 
-            SetStateInternal(pos, rot, scale, !shouldGhostsInterpolate);
+            SetStateInternal(pos, rot, scale, !teleportDisabled);
         }
 
         /// <summary>

Editor/AssemblyInfo.cs

@@ -1,3 +1,7 @@
 using System.Runtime.CompilerServices;
 
+#if UNITY_INCLUDE_TESTS
+#if UNITY_EDITOR
 [assembly: InternalsVisibleTo("Unity.Netcode.EditorTests")]
+#endif // UNITY_EDITOR
+#endif // UNITY_INCLUDE_TESTS

Editor/Configuration.meta

@@ -1,8 +1,3 @@
 fileFormatVersion: 2
-guid: 52153943c346dd04e8712ab540ab9c22
-folderAsset: yes
-DefaultImporter:
-  externalObjects: {}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 
+guid: b2f70916f7024c66aa5dfe1e43c151a2
+timeCreated: 1654274400

Editor/Configuration/NetcodeForGameObjectsSettings.cs

@@ -1,9 +1,10 @@
 using UnityEditor;
+using UnityEngine;
 
 
 namespace Unity.Netcode.Editor.Configuration
 {
-    internal class NetcodeForGameObjectsSettings
+    internal class NetcodeForGameObjectsEditorSettings
     {
         internal const string AutoAddNetworkObjectIfNoneExists = "AutoAdd-NetworkObject-When-None-Exist";
         internal const string InstallMultiplayerToolsTipDismissedPlayerPrefKey = "Netcode_Tip_InstallMPTools_Dismissed";
@@ -14,6 +15,7 @@ namespace Unity.Netcode.Editor.Configuration
             {
                 return EditorPrefs.GetInt(InstallMultiplayerToolsTipDismissedPlayerPrefKey);
             }
+
             return 0;
         }
 
@@ -28,6 +30,7 @@ namespace Unity.Netcode.Editor.Configuration
             {
                 return EditorPrefs.GetBool(AutoAddNetworkObjectIfNoneExists);
             }
+
             return false;
         }
 
@@ -36,4 +39,15 @@ namespace Unity.Netcode.Editor.Configuration
             EditorPrefs.SetBool(AutoAddNetworkObjectIfNoneExists, autoAddSetting);
         }
     }
+
+    [FilePath("ProjectSettings/NetcodeForGameObjects.settings", FilePathAttribute.Location.ProjectFolder)]
+    internal class NetcodeForGameObjectsProjectSettings : ScriptableSingleton<NetcodeForGameObjectsProjectSettings>
+    {
+        [SerializeField] public bool GenerateDefaultNetworkPrefabs = true;
+
+        internal void SaveSettings()
+        {
+            Save(true);
+        }
+    }
 }

Editor/Configuration/NetcodeSettingsProvider.cs

@@ -5,6 +5,11 @@ namespace Unity.Netcode.Editor.Configuration
 {
     internal static class NetcodeSettingsProvider
     {
+        private const float k_MaxLabelWidth = 450f;
+        private static float s_MaxLabelWidth;
+        private static bool s_ShowEditorSettingFields = true;
+        private static bool s_ShowProjectSettingFields = true;
+
         [SettingsProvider]
         public static SettingsProvider CreateNetcodeSettingsProvider()
         {
@@ -20,25 +25,105 @@ namespace Unity.Netcode.Editor.Configuration
             return provider;
         }
 
-        internal static NetcodeSettingsLabel NetworkObjectsSectionLabel = new NetcodeSettingsLabel("NetworkObject Helper Settings", 20);
-        internal static NetcodeSettingsToggle AutoAddNetworkObjectToggle = new NetcodeSettingsToggle("Auto-Add NetworkObjects", "When enabled, NetworkObjects are automatically added to GameObjects when NetworkBehaviours are added first.", 20);
-        internal static NetcodeSettingsLabel MultiplayerToolsLabel = new NetcodeSettingsLabel("Multiplayer Tools", 20);
-        internal static NetcodeSettingsToggle MultiplayerToolTipStatusToggle = new NetcodeSettingsToggle("Multiplayer Tools Install Reminder", "When enabled, the NetworkManager will display " +
-            "the notification to install the multiplayer tools package.", 20);
+
+        internal static NetcodeSettingsLabel NetworkObjectsSectionLabel;
+        internal static NetcodeSettingsToggle AutoAddNetworkObjectToggle;
+        internal static NetcodeSettingsLabel MultiplayerToolsLabel;
+        internal static NetcodeSettingsToggle MultiplayerToolTipStatusToggle;
+
+        /// <summary>
+        /// Creates an instance of the settings UI Elements if they don't already exist.
+        /// </summary>
+        /// <remarks>
+        /// We have to construct any NetcodeGUISettings derived classes here because in
+        /// version 2020.x.x EditorStyles.label does not exist yet (higher versions it does)
+        /// </remarks>
+        private static void CheckForInitialize()
+        {
+            if (NetworkObjectsSectionLabel == null)
+            {
+                NetworkObjectsSectionLabel = new NetcodeSettingsLabel("NetworkObject Helper Settings", 20);
+            }
+
+            if (AutoAddNetworkObjectToggle == null)
+            {
+                AutoAddNetworkObjectToggle = new NetcodeSettingsToggle("Auto-Add NetworkObject Component", "When enabled, NetworkObject components are automatically added to GameObjects when NetworkBehaviour components are added first.", 20);
+            }
+
+            if (MultiplayerToolsLabel == null)
+            {
+                MultiplayerToolsLabel = new NetcodeSettingsLabel("Multiplayer Tools", 20);
+            }
+
+            if (MultiplayerToolTipStatusToggle == null)
+            {
+                MultiplayerToolTipStatusToggle = new NetcodeSettingsToggle("Multiplayer Tools Install Reminder", "When enabled, the NetworkManager will display the notification to install the multiplayer tools package.", 20);
+            }
+        }
 
         private static void OnGuiHandler(string obj)
         {
-            var autoAddNetworkObjectSetting = NetcodeForGameObjectsSettings.GetAutoAddNetworkObjectSetting();
-            var multiplayerToolsTipStatus = NetcodeForGameObjectsSettings.GetNetcodeInstallMultiplayerToolTips() == 0;
+            // Make sure all NetcodeGUISettings derived classes are instantiated first
+            CheckForInitialize();
+
+            var autoAddNetworkObjectSetting = NetcodeForGameObjectsEditorSettings.GetAutoAddNetworkObjectSetting();
+            var multiplayerToolsTipStatus = NetcodeForGameObjectsEditorSettings.GetNetcodeInstallMultiplayerToolTips() == 0;
+            var settings = NetcodeForGameObjectsProjectSettings.instance;
+            var generateDefaultPrefabs = settings.GenerateDefaultNetworkPrefabs;
+
             EditorGUI.BeginChangeCheck();
-            NetworkObjectsSectionLabel.DrawLabel();
-            autoAddNetworkObjectSetting = AutoAddNetworkObjectToggle.DrawToggle(autoAddNetworkObjectSetting);
-            MultiplayerToolsLabel.DrawLabel();
-            multiplayerToolsTipStatus = MultiplayerToolTipStatusToggle.DrawToggle(multiplayerToolsTipStatus);
+
+            GUILayout.BeginVertical("Box");
+            s_ShowEditorSettingFields = EditorGUILayout.BeginFoldoutHeaderGroup(s_ShowEditorSettingFields, "Editor Settings");
+
+            if (s_ShowEditorSettingFields)
+            {
+                GUILayout.BeginVertical("Box");
+                NetworkObjectsSectionLabel.DrawLabel();
+                autoAddNetworkObjectSetting = AutoAddNetworkObjectToggle.DrawToggle(autoAddNetworkObjectSetting);
+                GUILayout.EndVertical();
+
+                GUILayout.BeginVertical("Box");
+                MultiplayerToolsLabel.DrawLabel();
+                multiplayerToolsTipStatus = MultiplayerToolTipStatusToggle.DrawToggle(multiplayerToolsTipStatus);
+                GUILayout.EndVertical();
+            }
+            EditorGUILayout.EndFoldoutHeaderGroup();
+            GUILayout.EndVertical();
+
+            GUILayout.BeginVertical("Box");
+            s_ShowProjectSettingFields = EditorGUILayout.BeginFoldoutHeaderGroup(s_ShowProjectSettingFields, "Project Settings");
+            if (s_ShowProjectSettingFields)
+            {
+                GUILayout.BeginVertical("Box");
+                const string generateNetworkPrefabsString = "Generate Default Network Prefabs List";
+
+                if (s_MaxLabelWidth == 0)
+                {
+                    s_MaxLabelWidth = EditorStyles.label.CalcSize(new GUIContent(generateNetworkPrefabsString)).x;
+                    s_MaxLabelWidth = Mathf.Min(k_MaxLabelWidth, s_MaxLabelWidth);
+                }
+
+                EditorGUIUtility.labelWidth = s_MaxLabelWidth;
+
+                GUILayout.Label("Network Prefabs", EditorStyles.boldLabel);
+                generateDefaultPrefabs = EditorGUILayout.Toggle(
+                    new GUIContent(
+                        generateNetworkPrefabsString,
+                        "When enabled, a default NetworkPrefabsList object will be added to your project and kept up " +
+                        "to date with all NetworkObject prefabs."),
+                    generateDefaultPrefabs,
+                    GUILayout.Width(s_MaxLabelWidth + 20));
+                GUILayout.EndVertical();
+            }
+            EditorGUILayout.EndFoldoutHeaderGroup();
+            GUILayout.EndVertical();
             if (EditorGUI.EndChangeCheck())
             {
-                NetcodeForGameObjectsSettings.SetAutoAddNetworkObjectSetting(autoAddNetworkObjectSetting);
-                NetcodeForGameObjectsSettings.SetNetcodeInstallMultiplayerToolTips(multiplayerToolsTipStatus ? 0 : 1);
+                NetcodeForGameObjectsEditorSettings.SetAutoAddNetworkObjectSetting(autoAddNetworkObjectSetting);
+                NetcodeForGameObjectsEditorSettings.SetNetcodeInstallMultiplayerToolTips(multiplayerToolsTipStatus ? 0 : 1);
+                settings.GenerateDefaultNetworkPrefabs = generateDefaultPrefabs;
+                settings.SaveSettings();
             }
         }
     }
@@ -56,7 +141,7 @@ namespace Unity.Netcode.Editor.Configuration
         public NetcodeSettingsLabel(string labelText, float layoutOffset = 0.0f)
         {
             m_LabelContent = labelText;
-            AdjustLableSize(labelText, layoutOffset);
+            AdjustLabelSize(labelText, layoutOffset);
         }
     }
 
@@ -72,7 +157,7 @@ namespace Unity.Netcode.Editor.Configuration
 
         public NetcodeSettingsToggle(string labelText, string toolTip, float layoutOffset)
         {
-            AdjustLableSize(labelText, layoutOffset);
+            AdjustLabelSize(labelText, layoutOffset);
             m_ToggleContent = new GUIContent(labelText, toolTip);
         }
     }
@@ -84,7 +169,7 @@ namespace Unity.Netcode.Editor.Configuration
 
         protected GUILayoutOption m_LayoutWidth { get; private set; }
 
-        protected void AdjustLableSize(string labelText, float offset = 0.0f)
+        protected void AdjustLabelSize(string labelText, float offset = 0.0f)
         {
             m_LabelSize = Mathf.Min(k_MaxLabelWidth, EditorStyles.label.CalcSize(new GUIContent(labelText)).x);
             m_LayoutWidth = GUILayout.Width(m_LabelSize + offset);

Editor/Configuration/NetworkPrefabProcessor.cs

@@ -0,0 +1,187 @@
+using System.Collections.Generic;
+using UnityEditor;
+using UnityEngine;
+
+namespace Unity.Netcode.Editor.Configuration
+{
+    /// <summary>
+    /// Updates the default <see cref="NetworkPrefabsList"/> instance when prefabs are updated (created, moved, deleted) in the project.
+    /// </summary>
+    public class NetworkPrefabProcessor : AssetPostprocessor
+    {
+        private static string s_DefaultNetworkPrefabsPath = "Assets/DefaultNetworkPrefabs.asset";
+        public static string DefaultNetworkPrefabsPath
+        {
+            get
+            {
+                return s_DefaultNetworkPrefabsPath;
+            }
+            internal set
+            {
+                s_DefaultNetworkPrefabsPath = value;
+                // Force a recache of the prefab list
+                s_PrefabsList = null;
+            }
+        }
+        private static NetworkPrefabsList s_PrefabsList;
+        private static Dictionary<string, NetworkPrefab> s_PrefabsListPath = new Dictionary<string, NetworkPrefab>();
+
+        private static void OnPostprocessAllAssets(string[] importedAssets, string[] deletedAssets, string[] movedAssets, string[] movedFromAssetPaths)
+        {
+            var settings = NetcodeForGameObjectsProjectSettings.instance;
+            if (!settings.GenerateDefaultNetworkPrefabs)
+            {
+                return;
+            }
+
+            bool ProcessImportedAssets(string[] importedAssets1)
+            {
+                var dirty = false;
+                foreach (var assetPath in importedAssets1)
+                {
+                    // We only care about GameObjects, skip everything else. Can't use the more targeted
+                    // OnPostProcessPrefabs since that's not called for moves or deletes
+                    if (AssetDatabase.GetMainAssetTypeAtPath(assetPath) != typeof(GameObject))
+                    {
+                        continue;
+                    }
+
+                    var go = AssetDatabase.LoadAssetAtPath<GameObject>(assetPath);
+                    if (go.TryGetComponent<NetworkObject>(out _))
+                    {
+                        // Make sure we are not duplicating an already existing entry
+                        if (s_PrefabsListPath.ContainsKey(assetPath))
+                        {
+                            // Is the imported asset different from the one we already have in the list?
+                            if (s_PrefabsListPath[assetPath].Prefab.GetHashCode() != go.GetHashCode())
+                            {
+                                // If so remove the one in the list and continue on to add the imported one
+                                s_PrefabsList.List.Remove(s_PrefabsListPath[assetPath]);
+                            }
+                            else // If they are identical, then just ignore the import
+                            {
+                                continue;
+                            }
+                        }
+
+                        s_PrefabsList.List.Add(new NetworkPrefab { Prefab = go });
+                        dirty = true;
+                    }
+                }
+
+                return dirty;
+            }
+
+            bool ProcessDeletedAssets(string[] strings)
+            {
+                var dirty = false;
+                var deleted = new List<string>(strings);
+                for (int i = s_PrefabsList.List.Count - 1; i >= 0 && deleted.Count > 0; --i)
+                {
+                    GameObject prefab;
+                    try
+                    {
+                        prefab = s_PrefabsList.List[i].Prefab;
+                    }
+                    catch (MissingReferenceException)
+                    {
+                        s_PrefabsList.List.RemoveAt(i);
+                        continue;
+                    }
+                    if (prefab == null)
+                    {
+                        s_PrefabsList.List.RemoveAt(i);
+                    }
+                    else
+                    {
+                        string noPath = AssetDatabase.GetAssetPath(prefab);
+                        for (int j = strings.Length - 1; j >= 0; --j)
+                        {
+                            if (noPath == strings[j])
+                            {
+                                s_PrefabsList.List.RemoveAt(i);
+                                deleted.RemoveAt(j);
+                                dirty = true;
+                            }
+                        }
+                    }
+                }
+
+                return dirty;
+            }
+
+            if (s_PrefabsList == null)
+            {
+                s_PrefabsList = GetOrCreateNetworkPrefabs(DefaultNetworkPrefabsPath, out var newList, true);
+                // A new list already processed all existing assets, no need to double-process imports & deletes
+                if (newList)
+                {
+                    return;
+                }
+            }
+            // Clear our asset path to prefab table each time
+            s_PrefabsListPath.Clear();
+
+            // Create our asst path to prefab table
+            foreach (var prefabEntry in s_PrefabsList.List)
+            {
+                if (!s_PrefabsListPath.ContainsKey(AssetDatabase.GetAssetPath(prefabEntry.Prefab)))
+                {
+                    s_PrefabsListPath.Add(AssetDatabase.GetAssetPath(prefabEntry.Prefab), prefabEntry);
+                }
+            }
+
+            // Process the imported and deleted assets
+            var markDirty = ProcessImportedAssets(importedAssets);
+            markDirty &= ProcessDeletedAssets(deletedAssets);
+
+            if (markDirty)
+            {
+                EditorUtility.SetDirty(s_PrefabsList);
+            }
+        }
+
+        internal static NetworkPrefabsList GetOrCreateNetworkPrefabs(string path, out bool isNew, bool addAll)
+        {
+            var defaultPrefabs = AssetDatabase.LoadAssetAtPath<NetworkPrefabsList>(path);
+            if (defaultPrefabs == null)
+            {
+                isNew = true;
+                defaultPrefabs = ScriptableObject.CreateInstance<NetworkPrefabsList>();
+                defaultPrefabs.IsDefault = true;
+                AssetDatabase.CreateAsset(defaultPrefabs, path);
+
+                if (addAll)
+                {
+                    // This could be very expensive in large projects... maybe make it manually triggered via a menu?
+                    defaultPrefabs.List = FindAll();
+                }
+                EditorUtility.SetDirty(defaultPrefabs);
+                AssetDatabase.SaveAssetIfDirty(defaultPrefabs);
+                return defaultPrefabs;
+            }
+
+            isNew = false;
+            return defaultPrefabs;
+        }
+
+        private static List<NetworkPrefab> FindAll()
+        {
+            var list = new List<NetworkPrefab>();
+
+            string[] guids = AssetDatabase.FindAssets("t:GameObject");
+            foreach (var guid in guids)
+            {
+                string assetPath = AssetDatabase.GUIDToAssetPath(guid);
+                var go = AssetDatabase.LoadAssetAtPath<GameObject>(assetPath);
+
+                if (go.TryGetComponent(out NetworkObject _))
+                {
+                    list.Add(new NetworkPrefab { Prefab = go });
+                }
+            }
+
+            return list;
+        }
+    }
+}

Editor/Configuration/NetworkPrefabProcessor.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: d8b62a05d80cc444f9c74731c01b8e39
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Editor/Configuration/NetworkPrefabsEditor.cs

@@ -0,0 +1,97 @@
+using UnityEditor;
+using UnityEditorInternal;
+using UnityEngine;
+
+namespace Unity.Netcode.Editor
+{
+    [CustomEditor(typeof(NetworkPrefabsList), true)]
+    [CanEditMultipleObjects]
+    public class NetworkPrefabsEditor : UnityEditor.Editor
+    {
+        private ReorderableList m_NetworkPrefabsList;
+        private SerializedProperty m_IsDefaultBool;
+
+        private void OnEnable()
+        {
+            m_IsDefaultBool = serializedObject.FindProperty(nameof(NetworkPrefabsList.IsDefault));
+            m_NetworkPrefabsList = new ReorderableList(serializedObject, serializedObject.FindProperty("List"), true, true, true, true);
+            m_NetworkPrefabsList.elementHeightCallback = index =>
+            {
+                var networkOverrideInt = 0;
+                if (m_NetworkPrefabsList.count > 0)
+                {
+                    var networkPrefab = m_NetworkPrefabsList.serializedProperty.GetArrayElementAtIndex(index);
+                    var networkOverrideProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.Override));
+                    networkOverrideInt = networkOverrideProp.enumValueIndex;
+                }
+
+                return 8 + (networkOverrideInt == 0 ? EditorGUIUtility.singleLineHeight : (EditorGUIUtility.singleLineHeight * 2) + 5);
+            };
+            m_NetworkPrefabsList.drawElementCallback = (rect, index, isActive, isFocused) =>
+            {
+                rect.y += 5;
+
+                var networkPrefab = m_NetworkPrefabsList.serializedProperty.GetArrayElementAtIndex(index);
+                var networkPrefabProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.Prefab));
+                var networkSourceHashProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.SourceHashToOverride));
+                var networkSourcePrefabProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.SourcePrefabToOverride));
+                var networkTargetPrefabProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.OverridingTargetPrefab));
+                var networkOverrideProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.Override));
+                var networkOverrideInt = networkOverrideProp.enumValueIndex;
+                var networkOverrideEnum = (NetworkPrefabOverride)networkOverrideInt;
+                EditorGUI.LabelField(new Rect(rect.x + rect.width - 70, rect.y, 60, EditorGUIUtility.singleLineHeight), "Override");
+                if (networkOverrideEnum == NetworkPrefabOverride.None)
+                {
+                    if (EditorGUI.Toggle(new Rect(rect.x + rect.width - 15, rect.y, 10, EditorGUIUtility.singleLineHeight), false))
+                    {
+                        networkOverrideProp.enumValueIndex = (int)NetworkPrefabOverride.Prefab;
+                    }
+                }
+                else
+                {
+                    if (!EditorGUI.Toggle(new Rect(rect.x + rect.width - 15, rect.y, 10, EditorGUIUtility.singleLineHeight), true))
+                    {
+                        networkOverrideProp.enumValueIndex = 0;
+                        networkOverrideEnum = NetworkPrefabOverride.None;
+                    }
+                }
+
+                if (networkOverrideEnum == NetworkPrefabOverride.None)
+                {
+                    EditorGUI.PropertyField(new Rect(rect.x, rect.y, rect.width - 80, EditorGUIUtility.singleLineHeight), networkPrefabProp, GUIContent.none);
+                }
+                else
+                {
+                    networkOverrideProp.enumValueIndex = GUI.Toolbar(new Rect(rect.x, rect.y, 100, EditorGUIUtility.singleLineHeight), networkOverrideInt - 1, new[] { "Prefab", "Hash" }) + 1;
+
+                    if (networkOverrideEnum == NetworkPrefabOverride.Prefab)
+                    {
+                        EditorGUI.PropertyField(new Rect(rect.x + 110, rect.y, rect.width - 190, EditorGUIUtility.singleLineHeight), networkSourcePrefabProp, GUIContent.none);
+                    }
+                    else
+                    {
+                        EditorGUI.PropertyField(new Rect(rect.x + 110, rect.y, rect.width - 190, EditorGUIUtility.singleLineHeight), networkSourceHashProp, GUIContent.none);
+                    }
+
+                    rect.y += EditorGUIUtility.singleLineHeight + 5;
+
+                    EditorGUI.LabelField(new Rect(rect.x, rect.y, 100, EditorGUIUtility.singleLineHeight), "Overriding Prefab");
+                    EditorGUI.PropertyField(new Rect(rect.x + 110, rect.y, rect.width - 110, EditorGUIUtility.singleLineHeight), networkTargetPrefabProp, GUIContent.none);
+                }
+            };
+            m_NetworkPrefabsList.drawHeaderCallback = rect => EditorGUI.LabelField(rect, "NetworkPrefabs");
+        }
+
+        public override void OnInspectorGUI()
+        {
+            using (new EditorGUI.DisabledScope(true))
+            {
+                EditorGUILayout.PropertyField(m_IsDefaultBool);
+            }
+
+            m_NetworkPrefabsList.DoLayoutList();
+
+            serializedObject.ApplyModifiedProperties();
+        }
+    }
+}

Editor/Configuration/NetworkPrefabsEditor.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 8d6d0919fa8ff41c9b1d1241256f7364
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Editor/HiddenScriptEditor.cs

@@ -4,6 +4,7 @@ using Unity.Netcode.Transports.UNET;
 #endif
 using Unity.Netcode.Transports.UTP;
 using UnityEditor;
+using UnityEngine;
 
 namespace Unity.Netcode.Editor
 {
@@ -43,7 +44,109 @@ namespace Unity.Netcode.Editor
     [CustomEditor(typeof(UnityTransport), true)]
     public class UnityTransportEditor : HiddenScriptEditor
     {
+        private static readonly string[] k_HiddenFields = { "m_Script", "ConnectionData" };
 
+        private bool m_AllowIncomingConnections;
+        private bool m_Initialized;
+
+        private UnityTransport m_UnityTransport;
+
+        private SerializedProperty m_ServerAddressProperty;
+        private SerializedProperty m_ServerPortProperty;
+        private SerializedProperty m_OverrideBindIpProperty;
+
+        private const string k_LoopbackIpv4 = "127.0.0.1";
+        private const string k_LoopbackIpv6 = "::1";
+        private const string k_AnyIpv4 = "0.0.0.0";
+        private const string k_AnyIpv6 = "::";
+
+
+        private void Initialize()
+        {
+            if (m_Initialized)
+            {
+                return;
+            }
+            m_Initialized = true;
+            m_UnityTransport = (UnityTransport)target;
+
+            var connectionDataProperty = serializedObject.FindProperty(nameof(UnityTransport.ConnectionData));
+
+            m_ServerAddressProperty = connectionDataProperty.FindPropertyRelative(nameof(UnityTransport.ConnectionAddressData.Address));
+            m_ServerPortProperty = connectionDataProperty.FindPropertyRelative(nameof(UnityTransport.ConnectionAddressData.Port));
+            m_OverrideBindIpProperty = connectionDataProperty.FindPropertyRelative(nameof(UnityTransport.ConnectionAddressData.ServerListenAddress));
+        }
+
+        /// <summary>
+        /// Draws inspector properties without the script field.
+        /// </summary>
+        public override void OnInspectorGUI()
+        {
+            Initialize();
+            EditorGUI.BeginChangeCheck();
+            serializedObject.UpdateIfRequiredOrScript();
+            DrawPropertiesExcluding(serializedObject, k_HiddenFields);
+            serializedObject.ApplyModifiedProperties();
+            EditorGUI.EndChangeCheck();
+
+            EditorGUILayout.PropertyField(m_ServerAddressProperty);
+            EditorGUILayout.PropertyField(m_ServerPortProperty);
+
+            serializedObject.ApplyModifiedProperties();
+
+            EditorGUILayout.HelpBox("It's recommended to leave remote connections disabled for local testing to avoid exposing ports on your device.", MessageType.Info);
+            bool allowRemoteConnections = m_UnityTransport.ConnectionData.ServerListenAddress != k_LoopbackIpv4 && m_UnityTransport.ConnectionData.ServerListenAddress != k_LoopbackIpv6 && !string.IsNullOrEmpty(m_UnityTransport.ConnectionData.ServerListenAddress);
+            allowRemoteConnections = EditorGUILayout.Toggle(new GUIContent("Allow Remote Connections?", $"Bind IP: {m_UnityTransport.ConnectionData.ServerListenAddress}"), allowRemoteConnections);
+
+            bool isIpV6 = m_UnityTransport.ConnectionData.IsIpv6;
+
+            if (!allowRemoteConnections)
+            {
+                if (m_UnityTransport.ConnectionData.ServerListenAddress != k_LoopbackIpv4 && m_UnityTransport.ConnectionData.ServerListenAddress != k_LoopbackIpv6)
+                {
+                    if (isIpV6)
+                    {
+                        m_UnityTransport.ConnectionData.ServerListenAddress = k_LoopbackIpv6;
+                    }
+                    else
+                    {
+                        m_UnityTransport.ConnectionData.ServerListenAddress = k_LoopbackIpv4;
+                    }
+                    EditorUtility.SetDirty(m_UnityTransport);
+                }
+            }
+
+            using (new EditorGUI.DisabledScope(!allowRemoteConnections))
+            {
+                string overrideIp = m_UnityTransport.ConnectionData.ServerListenAddress;
+                if (overrideIp == k_AnyIpv4 || overrideIp == k_AnyIpv6 || overrideIp == k_LoopbackIpv4 || overrideIp == k_LoopbackIpv6)
+                {
+                    overrideIp = "";
+                }
+
+                overrideIp = EditorGUILayout.TextField("Override Bind IP (optional)", overrideIp);
+                if (allowRemoteConnections)
+                {
+                    if (overrideIp == "")
+                    {
+                        if (isIpV6)
+                        {
+                            overrideIp = k_AnyIpv6;
+                        }
+                        else
+                        {
+                            overrideIp = k_AnyIpv4;
+                        }
+                    }
+
+                    if (m_UnityTransport.ConnectionData.ServerListenAddress != overrideIp)
+                    {
+                        m_UnityTransport.ConnectionData.ServerListenAddress = overrideIp;
+                        EditorUtility.SetDirty(m_UnityTransport);
+                    }
+                }
+            }
+        }
     }
 
 #if COM_UNITY_MODULES_ANIMATION

Editor/NetworkBehaviourEditor.cs

@@ -20,6 +20,7 @@ namespace Unity.Netcode.Editor
         private readonly Dictionary<string, object> m_NetworkVariableObjects = new Dictionary<string, object>();
 
         private GUIContent m_NetworkVariableLabelGuiContent;
+        private GUIContent m_NetworkListLabelGuiContent;
 
         private void Init(MonoScript script)
         {
@@ -30,6 +31,7 @@ namespace Unity.Netcode.Editor
             m_NetworkVariableObjects.Clear();
 
             m_NetworkVariableLabelGuiContent = new GUIContent("NetworkVariable", "This variable is a NetworkVariable. It can not be serialized and can only be changed during runtime.");
+            m_NetworkListLabelGuiContent = new GUIContent("NetworkList", "This variable is a NetworkList. It is rendered, but you can't serialize or change it.");
 
             var fields = script.GetClass().GetFields(BindingFlags.Public | BindingFlags.Instance | BindingFlags.FlattenHierarchy);
             for (int i = 0; i < fields.Length; i++)
@@ -39,6 +41,13 @@ namespace Unity.Netcode.Editor
                 {
                     m_NetworkVariableNames.Add(ObjectNames.NicifyVariableName(fields[i].Name));
                     m_NetworkVariableFields.Add(ObjectNames.NicifyVariableName(fields[i].Name), fields[i]);
+                    Debug.Log($"Adding NetworkVariable {fields[i].Name}");
+                }
+                if (ft.IsGenericType && ft.GetGenericTypeDefinition() == typeof(NetworkList<>) && !fields[i].IsDefined(typeof(HideInInspector), true))
+                {
+                    m_NetworkVariableNames.Add(ObjectNames.NicifyVariableName(fields[i].Name));
+                    m_NetworkVariableFields.Add(ObjectNames.NicifyVariableName(fields[i].Name), fields[i]);
+                    Debug.Log($"Adding NetworkList {fields[i].Name}");
                 }
             }
         }
@@ -72,25 +81,48 @@ namespace Unity.Netcode.Editor
             EditorGUILayout.BeginHorizontal();
             if (genericType.IsValueType)
             {
-                var method = typeof(NetworkBehaviourEditor).GetMethod("RenderNetworkVariableValueType", BindingFlags.Public | BindingFlags.Instance | BindingFlags.FlattenHierarchy | BindingFlags.NonPublic);
+                var method = typeof(NetworkBehaviourEditor).GetMethod("RenderNetworkContainerValueType", BindingFlags.Public | BindingFlags.Instance | BindingFlags.FlattenHierarchy | BindingFlags.NonPublic);
                 var genericMethod = method.MakeGenericMethod(genericType);
                 genericMethod.Invoke(this, new[] { (object)index });
             }
             else
             {
                 EditorGUILayout.LabelField("Type not renderable");
+
+                GUILayout.Label(m_NetworkVariableLabelGuiContent, EditorStyles.miniLabel, GUILayout.Width(EditorStyles.miniLabel.CalcSize(m_NetworkVariableLabelGuiContent).x));
+                EditorGUILayout.EndHorizontal();
+            }
+        }
+
+        private void RenderNetworkContainerValueType<T>(int index) where T : unmanaged, IEquatable<T>
+        {
+            try
+            {
+                var networkVariable = (NetworkVariable<T>)m_NetworkVariableFields[m_NetworkVariableNames[index]].GetValue(target);
+                RenderNetworkVariableValueType(index, networkVariable);
+            }
+            catch (Exception)
+            {
+                try
+                {
+                    var networkList = (NetworkList<T>)m_NetworkVariableFields[m_NetworkVariableNames[index]].GetValue(target);
+                    RenderNetworkListValueType(index, networkList);
+                }
+                catch (Exception e)
+                {
+                    Debug.Log(e);
+                    throw;
+                }
             }
 
-            GUILayout.Label(m_NetworkVariableLabelGuiContent, EditorStyles.miniLabel, GUILayout.Width(EditorStyles.miniLabel.CalcSize(m_NetworkVariableLabelGuiContent).x));
             EditorGUILayout.EndHorizontal();
         }
 
-        private void RenderNetworkVariableValueType<T>(int index) where T : unmanaged
+        private void RenderNetworkVariableValueType<T>(int index, NetworkVariable<T> networkVariable) where T : unmanaged
         {
-            var networkVariable = (NetworkVariable<T>)m_NetworkVariableFields[m_NetworkVariableNames[index]].GetValue(target);
             var type = typeof(T);
             object val = networkVariable.Value;
-            string name = m_NetworkVariableNames[index];
+            string variableName = m_NetworkVariableNames[index];
 
             var behaviour = (NetworkBehaviour)target;
 
@@ -99,47 +131,47 @@ namespace Unity.Netcode.Editor
             {
                 if (type == typeof(int))
                 {
-                    val = EditorGUILayout.IntField(name, (int)val);
+                    val = EditorGUILayout.IntField(variableName, (int)val);
                 }
                 else if (type == typeof(uint))
                 {
-                    val = (uint)EditorGUILayout.LongField(name, (long)((uint)val));
+                    val = (uint)EditorGUILayout.LongField(variableName, (long)((uint)val));
                 }
                 else if (type == typeof(short))
                 {
-                    val = (short)EditorGUILayout.IntField(name, (int)((short)val));
+                    val = (short)EditorGUILayout.IntField(variableName, (int)((short)val));
                 }
                 else if (type == typeof(ushort))
                 {
-                    val = (ushort)EditorGUILayout.IntField(name, (int)((ushort)val));
+                    val = (ushort)EditorGUILayout.IntField(variableName, (int)((ushort)val));
                 }
                 else if (type == typeof(sbyte))
                 {
-                    val = (sbyte)EditorGUILayout.IntField(name, (int)((sbyte)val));
+                    val = (sbyte)EditorGUILayout.IntField(variableName, (int)((sbyte)val));
                 }
                 else if (type == typeof(byte))
                 {
-                    val = (byte)EditorGUILayout.IntField(name, (int)((byte)val));
+                    val = (byte)EditorGUILayout.IntField(variableName, (int)((byte)val));
                 }
                 else if (type == typeof(long))
                 {
-                    val = EditorGUILayout.LongField(name, (long)val);
+                    val = EditorGUILayout.LongField(variableName, (long)val);
                 }
                 else if (type == typeof(ulong))
                 {
-                    val = (ulong)EditorGUILayout.LongField(name, (long)((ulong)val));
+                    val = (ulong)EditorGUILayout.LongField(variableName, (long)((ulong)val));
                 }
                 else if (type == typeof(bool))
                 {
-                    val = EditorGUILayout.Toggle(name, (bool)val);
+                    val = EditorGUILayout.Toggle(variableName, (bool)val);
                 }
                 else if (type == typeof(string))
                 {
-                    val = EditorGUILayout.TextField(name, (string)val);
+                    val = EditorGUILayout.TextField(variableName, (string)val);
                 }
                 else if (type.IsEnum)
                 {
-                    val = EditorGUILayout.EnumPopup(name, (Enum)val);
+                    val = EditorGUILayout.EnumPopup(variableName, (Enum)val);
                 }
                 else
                 {
@@ -150,11 +182,31 @@ namespace Unity.Netcode.Editor
             }
             else
             {
-                EditorGUILayout.LabelField(name, EditorStyles.wordWrappedLabel);
+                EditorGUILayout.LabelField(variableName, EditorStyles.wordWrappedLabel);
                 EditorGUILayout.SelectableLabel(val.ToString(), EditorStyles.wordWrappedLabel);
             }
+            GUILayout.Label(m_NetworkVariableLabelGuiContent, EditorStyles.miniLabel, GUILayout.Width(EditorStyles.miniLabel.CalcSize(m_NetworkVariableLabelGuiContent).x));
         }
 
+        private void RenderNetworkListValueType<T>(int index, NetworkList<T> networkList)
+            where T : unmanaged, IEquatable<T>
+        {
+            string variableName = m_NetworkVariableNames[index];
+
+            string value = "";
+            bool addComma = false;
+            foreach (var v in networkList)
+            {
+                if (addComma)
+                {
+                    value += ", ";
+                }
+                value += v.ToString();
+                addComma = true;
+            }
+            EditorGUILayout.LabelField(variableName, value);
+            GUILayout.Label(m_NetworkListLabelGuiContent, EditorStyles.miniLabel, GUILayout.Width(EditorStyles.miniLabel.CalcSize(m_NetworkListLabelGuiContent).x));
+        }
 
         /// <inheritdoc/>
         public override void OnInspectorGUI()
@@ -310,7 +362,7 @@ namespace Unity.Netcode.Editor
                     // and the user has already turned "Auto-Add NetworkObject" on when first notified about the requirement
                     // then just send a reminder to the user why the NetworkObject they just deleted seemingly "re-appeared"
                     // again.
-                    if (networkObjectRemoved && NetcodeForGameObjectsSettings.GetAutoAddNetworkObjectSetting())
+                    if (networkObjectRemoved && NetcodeForGameObjectsEditorSettings.GetAutoAddNetworkObjectSetting())
                     {
                         Debug.LogWarning($"{gameObject.name} still has {nameof(NetworkBehaviour)}s and Auto-Add NetworkObjects is enabled. A NetworkObject is being added back to {gameObject.name}.");
                         Debug.Log($"To reset Auto-Add NetworkObjects: Select the Netcode->General->Reset Auto-Add NetworkObject menu item.");
@@ -319,7 +371,7 @@ namespace Unity.Netcode.Editor
                     // Notify and provide the option to add it one time, always add a NetworkObject, or do nothing and let the user manually add it
                     if (EditorUtility.DisplayDialog($"{nameof(NetworkBehaviour)}s require a {nameof(NetworkObject)}",
                     $"{gameObject.name} does not have a {nameof(NetworkObject)} component.  Would you like to add one now?", "Yes", "No (manually add it)",
-                    DialogOptOutDecisionType.ForThisMachine, NetcodeForGameObjectsSettings.AutoAddNetworkObjectIfNoneExists))
+                    DialogOptOutDecisionType.ForThisMachine, NetcodeForGameObjectsEditorSettings.AutoAddNetworkObjectIfNoneExists))
                     {
                         gameObject.AddComponent<NetworkObject>();
                         var activeScene = UnityEngine.SceneManagement.SceneManager.GetActiveScene();

Editor/NetworkManagerEditor.cs

@@ -1,8 +1,8 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using UnityEditor;
 using UnityEngine;
-using UnityEditorInternal;
 using Unity.Netcode.Editor.Configuration;
 
 namespace Unity.Netcode.Editor
@@ -40,8 +40,7 @@ namespace Unity.Netcode.Editor
         private SerializedProperty m_NetworkIdRecycleDelayProperty;
         private SerializedProperty m_RpcHashSizeProperty;
         private SerializedProperty m_LoadSceneTimeOutProperty;
-
-        private ReorderableList m_NetworkPrefabsList;
+        private SerializedProperty m_PrefabsList;
 
         private NetworkManager m_NetworkManager;
         private bool m_Initialized;
@@ -106,7 +105,9 @@ namespace Unity.Netcode.Editor
             m_NetworkIdRecycleDelayProperty = m_NetworkConfigProperty.FindPropertyRelative("NetworkIdRecycleDelay");
             m_RpcHashSizeProperty = m_NetworkConfigProperty.FindPropertyRelative("RpcHashSize");
             m_LoadSceneTimeOutProperty = m_NetworkConfigProperty.FindPropertyRelative("LoadSceneTimeOut");
-
+            m_PrefabsList = m_NetworkConfigProperty
+                .FindPropertyRelative(nameof(NetworkConfig.Prefabs))
+                .FindPropertyRelative(nameof(NetworkPrefabs.NetworkPrefabsLists));
 
             ReloadTransports();
         }
@@ -132,76 +133,9 @@ namespace Unity.Netcode.Editor
             m_NetworkIdRecycleDelayProperty = m_NetworkConfigProperty.FindPropertyRelative("NetworkIdRecycleDelay");
             m_RpcHashSizeProperty = m_NetworkConfigProperty.FindPropertyRelative("RpcHashSize");
             m_LoadSceneTimeOutProperty = m_NetworkConfigProperty.FindPropertyRelative("LoadSceneTimeOut");
-        }
-
-        private void OnEnable()
-        {
-            m_NetworkPrefabsList = new ReorderableList(serializedObject, serializedObject.FindProperty(nameof(NetworkManager.NetworkConfig)).FindPropertyRelative(nameof(NetworkConfig.NetworkPrefabs)), true, true, true, true);
-            m_NetworkPrefabsList.elementHeightCallback = index =>
-            {
-                var networkOverrideInt = 0;
-                if (m_NetworkPrefabsList.count > 0)
-                {
-                    var networkPrefab = m_NetworkPrefabsList.serializedProperty.GetArrayElementAtIndex(index);
-                    var networkOverrideProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.Override));
-                    networkOverrideInt = networkOverrideProp.enumValueIndex;
-                }
-
-                return 8 + (networkOverrideInt == 0 ? EditorGUIUtility.singleLineHeight : (EditorGUIUtility.singleLineHeight * 2) + 5);
-            };
-            m_NetworkPrefabsList.drawElementCallback = (rect, index, isActive, isFocused) =>
-            {
-                rect.y += 5;
-
-                var networkPrefab = m_NetworkPrefabsList.serializedProperty.GetArrayElementAtIndex(index);
-                var networkPrefabProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.Prefab));
-                var networkSourceHashProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.SourceHashToOverride));
-                var networkSourcePrefabProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.SourcePrefabToOverride));
-                var networkTargetPrefabProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.OverridingTargetPrefab));
-                var networkOverrideProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.Override));
-                var networkOverrideInt = networkOverrideProp.enumValueIndex;
-                var networkOverrideEnum = (NetworkPrefabOverride)networkOverrideInt;
-                EditorGUI.LabelField(new Rect(rect.x + rect.width - 70, rect.y, 60, EditorGUIUtility.singleLineHeight), "Override");
-                if (networkOverrideEnum == NetworkPrefabOverride.None)
-                {
-                    if (EditorGUI.Toggle(new Rect(rect.x + rect.width - 15, rect.y, 10, EditorGUIUtility.singleLineHeight), false))
-                    {
-                        networkOverrideProp.enumValueIndex = (int)NetworkPrefabOverride.Prefab;
-                    }
-                }
-                else
-                {
-                    if (!EditorGUI.Toggle(new Rect(rect.x + rect.width - 15, rect.y, 10, EditorGUIUtility.singleLineHeight), true))
-                    {
-                        networkOverrideProp.enumValueIndex = 0;
-                        networkOverrideEnum = NetworkPrefabOverride.None;
-                    }
-                }
-
-                if (networkOverrideEnum == NetworkPrefabOverride.None)
-                {
-                    EditorGUI.PropertyField(new Rect(rect.x, rect.y, rect.width - 80, EditorGUIUtility.singleLineHeight), networkPrefabProp, GUIContent.none);
-                }
-                else
-                {
-                    networkOverrideProp.enumValueIndex = GUI.Toolbar(new Rect(rect.x, rect.y, 100, EditorGUIUtility.singleLineHeight), networkOverrideInt - 1, new[] { "Prefab", "Hash" }) + 1;
-
-                    if (networkOverrideEnum == NetworkPrefabOverride.Prefab)
-                    {
-                        EditorGUI.PropertyField(new Rect(rect.x + 110, rect.y, rect.width - 190, EditorGUIUtility.singleLineHeight), networkSourcePrefabProp, GUIContent.none);
-                    }
-                    else
-                    {
-                        EditorGUI.PropertyField(new Rect(rect.x + 110, rect.y, rect.width - 190, EditorGUIUtility.singleLineHeight), networkSourceHashProp, GUIContent.none);
-                    }
-
-                    rect.y += EditorGUIUtility.singleLineHeight + 5;
-
-                    EditorGUI.LabelField(new Rect(rect.x, rect.y, 100, EditorGUIUtility.singleLineHeight), "Overriding Prefab");
-                    EditorGUI.PropertyField(new Rect(rect.x + 110, rect.y, rect.width - 110, EditorGUIUtility.singleLineHeight), networkTargetPrefabProp, GUIContent.none);
-                }
-            };
-            m_NetworkPrefabsList.drawHeaderCallback = rect => EditorGUI.LabelField(rect, "NetworkPrefabs");
+            m_PrefabsList = m_NetworkConfigProperty
+                .FindPropertyRelative(nameof(NetworkConfig.Prefabs))
+                .FindPropertyRelative(nameof(NetworkPrefabs.NetworkPrefabsLists));
         }
 
         /// <inheritdoc/>
@@ -224,7 +158,62 @@ namespace Unity.Netcode.Editor
                 EditorGUILayout.PropertyField(m_PlayerPrefabProperty);
                 EditorGUILayout.Space();
 
-                m_NetworkPrefabsList.DoLayoutList();
+                if (m_NetworkManager.NetworkConfig.HasOldPrefabList())
+                {
+                    EditorGUILayout.HelpBox("Network Prefabs serialized in old format. Migrate to new format to edit the list.", MessageType.Info);
+                    if (GUILayout.Button(new GUIContent("Migrate Prefab List", "Converts the old format Network Prefab list to a new Scriptable Object")))
+                    {
+                        // Default directory
+                        var directory = "Assets/";
+                        var assetPath = AssetDatabase.GetAssetPath(m_NetworkManager);
+                        if (assetPath == "")
+                        {
+                            assetPath = PrefabUtility.GetPrefabAssetPathOfNearestInstanceRoot(m_NetworkManager);
+                        }
+
+                        if (assetPath != "")
+                        {
+                            directory = Path.GetDirectoryName(assetPath);
+                        }
+                        else
+                        {
+#if UNITY_2021_1_OR_NEWER
+                            var prefabStage = UnityEditor.SceneManagement.PrefabStageUtility.GetPrefabStage(m_NetworkManager.gameObject);
+#else
+                            var prefabStage = UnityEditor.Experimental.SceneManagement.PrefabStageUtility.GetPrefabStage(m_NetworkManager.gameObject);
+#endif
+                            if (prefabStage != null)
+                            {
+                                var prefabPath = prefabStage.assetPath;
+                                if (!string.IsNullOrEmpty(prefabPath))
+                                {
+                                    directory = Path.GetDirectoryName(prefabPath);
+                                }
+                            }
+                            if (m_NetworkManager.gameObject.scene != null)
+                            {
+                                var scenePath = m_NetworkManager.gameObject.scene.path;
+                                if (!string.IsNullOrEmpty(scenePath))
+                                {
+                                    directory = Path.GetDirectoryName(scenePath);
+                                }
+                            }
+                        }
+                        var networkPrefabs = m_NetworkManager.NetworkConfig.MigrateOldNetworkPrefabsToNetworkPrefabsList();
+                        string path = Path.Combine(directory, $"NetworkPrefabs-{m_NetworkManager.GetInstanceID()}.asset");
+                        Debug.Log("Saving migrated Network Prefabs List to " + path);
+                        AssetDatabase.CreateAsset(networkPrefabs, path);
+                        EditorUtility.SetDirty(m_NetworkManager);
+                    }
+                }
+                else
+                {
+                    if (m_NetworkManager.NetworkConfig.Prefabs.NetworkPrefabsLists.Count == 0)
+                    {
+                        EditorGUILayout.HelpBox("You have no prefab list selected. You will have to add your prefabs manually at runtime for netcode to work.", MessageType.Warning);
+                    }
+                    EditorGUILayout.PropertyField(m_PrefabsList);
+                }
                 EditorGUILayout.Space();
 
                 EditorGUILayout.LabelField("General", EditorStyles.boldLabel);
@@ -359,7 +348,7 @@ namespace Unity.Netcode.Editor
             const string targetUrl = "https://docs-multiplayer.unity3d.com/netcode/current/tools/install-tools";
             const string infoIconName = "console.infoicon";
 
-            if (NetcodeForGameObjectsSettings.GetNetcodeInstallMultiplayerToolTips() != 0)
+            if (NetcodeForGameObjectsEditorSettings.GetNetcodeInstallMultiplayerToolTips() != 0)
             {
                 return;
             }
@@ -405,7 +394,7 @@ namespace Unity.Netcode.Editor
                 GUILayout.FlexibleSpace();
                 if (GUILayout.Button(dismissButtonText, dismissButtonStyle, GUILayout.ExpandWidth(false)))
                 {
-                    NetcodeForGameObjectsSettings.SetNetcodeInstallMultiplayerToolTips(1);
+                    NetcodeForGameObjectsEditorSettings.SetNetcodeInstallMultiplayerToolTips(1);
                 }
                 EditorGUIUtility.AddCursorRect(GUILayoutUtility.GetLastRect(), MouseCursor.Link);
                 GUILayout.FlexibleSpace();

Editor/NetworkManagerHelper.cs

@@ -1,5 +1,6 @@
 using System.Collections.Generic;
 using System.Linq;
+using Unity.Netcode.Editor.Configuration;
 using UnityEngine;
 using UnityEngine.SceneManagement;
 using UnityEditor;
@@ -32,6 +33,24 @@ namespace Unity.Netcode.Editor
 
             EditorApplication.playModeStateChanged += EditorApplication_playModeStateChanged;
             EditorApplication.hierarchyChanged += EditorApplication_hierarchyChanged;
+
+            // Initialize default values for new NetworkManagers
+            //
+            // When the default prefab list is enabled, this will default
+            // new NetworkManagers to using it.
+            //
+            // This will get run when new NetworkManagers are added, and
+            // when the user presses the "reset" button on a NetworkManager
+            // in the inspector.
+            NetworkManager.OnNetworkManagerReset = manager =>
+            {
+                var settings = NetcodeForGameObjectsProjectSettings.instance;
+                if (settings.GenerateDefaultNetworkPrefabs)
+                {
+                    manager.NetworkConfig = new NetworkConfig();
+                    manager.NetworkConfig.Prefabs.NetworkPrefabsLists = new List<NetworkPrefabsList> { NetworkPrefabProcessor.GetOrCreateNetworkPrefabs(NetworkPrefabProcessor.DefaultNetworkPrefabsPath, out _, true) };
+                }
+            };
         }
 
         private static void EditorApplication_playModeStateChanged(PlayModeStateChange playModeStateChange)

Runtime/AssemblyInfo.cs

@@ -1,15 +1,25 @@
 using System.Runtime.CompilerServices;
 
 #if UNITY_EDITOR
-[assembly: InternalsVisibleTo("Unity.Netcode.EditorTests")]
-[assembly: InternalsVisibleTo("Unity.Netcode.Editor.CodeGen")]
 [assembly: InternalsVisibleTo("Unity.Netcode.Editor")]
-[assembly: InternalsVisibleTo("TestProject.EditorTests")]
 [assembly: InternalsVisibleTo("Unity.Netcode.Editor.CodeGen")]
-#endif
-[assembly: InternalsVisibleTo("TestProject.ToolsIntegration.RuntimeTests")]
-[assembly: InternalsVisibleTo("TestProject.RuntimeTests")]
+#endif // UNITY_EDITOR
+#if MULTIPLAYER_TOOLS
+[assembly: InternalsVisibleTo("Unity.Multiplayer.Tools.Adapters.Ngo1WithUtp2")]
+#endif // MULTIPLAYER_TOOLS
+#if COM_UNITY_NETCODE_ADAPTER_UTP
+[assembly: InternalsVisibleTo("Unity.Netcode.Adapter.UTP")]
+#endif // COM_UNITY_NETCODE_ADAPTER_UTP
+
+#if UNITY_INCLUDE_TESTS
 [assembly: InternalsVisibleTo("Unity.Netcode.RuntimeTests")]
 [assembly: InternalsVisibleTo("Unity.Netcode.TestHelpers.Runtime")]
-[assembly: InternalsVisibleTo("Unity.Netcode.Adapter.UTP")]
-[assembly: InternalsVisibleTo("Unity.Multiplayer.Tools.Adapters.Ngo1WithUtp2")]
+[assembly: InternalsVisibleTo("TestProject.RuntimeTests")]
+#if UNITY_EDITOR
+[assembly: InternalsVisibleTo("Unity.Netcode.EditorTests")]
+[assembly: InternalsVisibleTo("TestProject.EditorTests")]
+#endif // UNITY_EDITOR
+#if MULTIPLAYER_TOOLS
+[assembly: InternalsVisibleTo("TestProject.ToolsIntegration.RuntimeTests")]
+#endif // MULTIPLAYER_TOOLS
+#endif // UNITY_INCLUDE_TESTS

Runtime/Configuration/NetworkConfig.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using UnityEngine;
 using System.Linq;
 using Unity.Collections;
+using UnityEngine.Serialization;
 
 namespace Unity.Netcode
 {
@@ -30,20 +31,8 @@ namespace Unity.Netcode
         [Tooltip("When set, NetworkManager will automatically create and spawn the assigned player prefab. This can be overridden by adding it to the NetworkPrefabs list and selecting override.")]
         public GameObject PlayerPrefab;
 
-        /// <summary>
-        /// A list of prefabs that can be dynamically spawned.
-        /// </summary>
         [SerializeField]
-        [Tooltip("The prefabs that can be spawned across the network")]
-        internal List<NetworkPrefab> NetworkPrefabs = new List<NetworkPrefab>();
-
-        /// <summary>
-        /// This dictionary provides a quick way to check and see if a NetworkPrefab has a NetworkPrefab override.
-        /// Generated at runtime and OnValidate
-        /// </summary>
-        internal Dictionary<uint, NetworkPrefab> NetworkPrefabOverrideLinks = new Dictionary<uint, NetworkPrefab>();
-
-        internal Dictionary<uint, uint> OverrideToNetworkPrefab = new Dictionary<uint, uint>();
+        public NetworkPrefabs Prefabs = new NetworkPrefabs();
 
 
         /// <summary>
@@ -239,7 +228,7 @@ namespace Unity.Netcode
 
                 if (ForceSamePrefabs)
                 {
-                    var sortedDictionary = NetworkPrefabOverrideLinks.OrderBy(x => x.Key);
+                    var sortedDictionary = Prefabs.NetworkPrefabOverrideLinks.OrderBy(x => x.Key);
                     foreach (var sortedEntry in sortedDictionary)
 
                     {
@@ -273,6 +262,79 @@ namespace Unity.Netcode
         {
             return hash == GetConfig();
         }
+
+        internal void InitializePrefabs()
+        {
+            if (HasOldPrefabList())
+            {
+                MigrateOldNetworkPrefabsToNetworkPrefabsList();
+            }
+
+            Prefabs.Initialize();
+        }
+
+        #region Legacy Network Prefab List
+
+        [NonSerialized]
+        private bool m_DidWarnOldPrefabList = false;
+
+        private void WarnOldPrefabList()
+        {
+            if (!m_DidWarnOldPrefabList)
+            {
+                Debug.LogWarning("Using Legacy Network Prefab List. Consider Migrating.");
+                m_DidWarnOldPrefabList = true;
+            }
+        }
+
+        /// <summary>
+        /// Returns true if the old List&lt;NetworkPrefab&gt; serialized data is present.
+        /// </summary>
+        /// <remarks>
+        /// Internal use only to help migrate projects. <seealso cref="MigrateOldNetworkPrefabsToNetworkPrefabsList"/></remarks>
+        internal bool HasOldPrefabList()
+        {
+            return OldPrefabList?.Count > 0;
+        }
+
+        /// <summary>
+        /// Migrate the old format List&lt;NetworkPrefab&gt; prefab registration to the new NetworkPrefabsList ScriptableObject.
+        /// </summary>
+        /// <remarks>
+        /// OnAfterDeserialize cannot instantiate new objects (e.g. NetworkPrefabsList SO) since it executes in a thread, so we have to do it later.
+        /// Since NetworkConfig isn't a Unity.Object it doesn't get an Awake callback, so we have to do this in NetworkManager and expose this API.
+        /// </remarks>
+        internal NetworkPrefabsList MigrateOldNetworkPrefabsToNetworkPrefabsList()
+        {
+            if (OldPrefabList == null || OldPrefabList.Count == 0)
+            {
+                return null;
+            }
+
+            if (Prefabs == null)
+            {
+                throw new Exception("Prefabs field is null.");
+            }
+
+            Prefabs.NetworkPrefabsLists.Add(ScriptableObject.CreateInstance<NetworkPrefabsList>());
+
+            if (OldPrefabList?.Count > 0)
+            {
+                // Migrate legacy types/fields
+                foreach (var networkPrefab in OldPrefabList)
+                {
+                    Prefabs.NetworkPrefabsLists[Prefabs.NetworkPrefabsLists.Count - 1].Add(networkPrefab);
+                }
+            }
+
+            OldPrefabList = null;
+            return Prefabs.NetworkPrefabsLists[Prefabs.NetworkPrefabsLists.Count - 1];
+        }
+
+        [FormerlySerializedAs("NetworkPrefabs")]
+        [SerializeField]
+        internal List<NetworkPrefab> OldPrefabList;
+
+        #endregion
     }
 }
-

Runtime/Configuration/NetworkPrefab.cs

@@ -3,10 +3,23 @@ using UnityEngine;
 
 namespace Unity.Netcode
 {
-    internal enum NetworkPrefabOverride
+    /// <summary>
+    /// The method of NetworkPrefab override used to identify the source prefab
+    /// </summary>
+    public enum NetworkPrefabOverride
     {
+        /// <summary>
+        /// No oeverride is present
+        /// </summary>
         None,
+        /// <summary>
+        /// Override the prefab when the given SourcePrefabToOverride is requested
+        /// </summary>
         Prefab,
+        /// <summary>
+        /// Override the prefab when the given SourceHashToOverride is requested
+        /// Used in situations where the server assets do not exist in client builds
+        /// </summary>
         Hash
     }
 
@@ -14,10 +27,10 @@ namespace Unity.Netcode
     /// Class that represents a NetworkPrefab
     /// </summary>
     [Serializable]
-    internal class NetworkPrefab
+    public class NetworkPrefab
     {
         /// <summary>
-        /// The override setttings for this NetworkPrefab
+        /// The override settings for this NetworkPrefab
         /// </summary>
         public NetworkPrefabOverride Override;
 
@@ -41,5 +54,168 @@ namespace Unity.Netcode
         /// The prefab to replace (override) the source prefab with
         /// </summary>
         public GameObject OverridingTargetPrefab;
+
+        public bool Equals(NetworkPrefab other)
+        {
+            return Override == other.Override &&
+                   Prefab == other.Prefab &&
+                   SourcePrefabToOverride == other.SourcePrefabToOverride &&
+                   SourceHashToOverride == other.SourceHashToOverride &&
+                   OverridingTargetPrefab == other.OverridingTargetPrefab;
+        }
+
+        public uint SourcePrefabGlobalObjectIdHash
+        {
+            get
+            {
+                switch (Override)
+                {
+                    case NetworkPrefabOverride.None:
+                        if (Prefab != null && Prefab.TryGetComponent(out NetworkObject no))
+                        {
+                            return no.GlobalObjectIdHash;
+                        }
+
+                        throw new InvalidOperationException("Prefab field isn't set or isn't a Network Object");
+                    case NetworkPrefabOverride.Prefab:
+                        if (SourcePrefabToOverride != null && SourcePrefabToOverride.TryGetComponent(out no))
+                        {
+                            return no.GlobalObjectIdHash;
+                        }
+
+                        throw new InvalidOperationException("Source Prefab field isn't set or isn't a Network Object");
+                    case NetworkPrefabOverride.Hash:
+                        return SourceHashToOverride;
+                    default:
+                        throw new ArgumentOutOfRangeException();
+                }
+            }
+        }
+
+        public uint TargetPrefabGlobalObjectIdHash
+        {
+            get
+            {
+                switch (Override)
+                {
+                    case NetworkPrefabOverride.None:
+                        return 0;
+                    case NetworkPrefabOverride.Prefab:
+                    case NetworkPrefabOverride.Hash:
+                        if (OverridingTargetPrefab != null && OverridingTargetPrefab.TryGetComponent(out NetworkObject no))
+                        {
+                            return no.GlobalObjectIdHash;
+                        }
+
+                        throw new InvalidOperationException("Target Prefab field isn't set or isn't a Network Object");
+                    default:
+                        throw new ArgumentOutOfRangeException();
+                }
+            }
+        }
+
+        public bool Validate(int index = -1)
+        {
+            NetworkObject networkObject;
+            if (Override == NetworkPrefabOverride.None)
+            {
+                if (Prefab == null)
+                {
+                    NetworkLog.LogWarning($"{nameof(NetworkPrefab)} cannot be null ({nameof(NetworkPrefab)} at index: {index})");
+                    return false;
+                }
+
+                networkObject = Prefab.GetComponent<NetworkObject>();
+                if (networkObject == null)
+                {
+                    if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
+                    {
+                        NetworkLog.LogWarning($"{NetworkManager.PrefabDebugHelper(this)} is missing " +
+                                              $"a {nameof(NetworkObject)} component (entry will be ignored).");
+                    }
+                    return false;
+                }
+
+                return true;
+            }
+
+            // Validate source prefab override values first
+            switch (Override)
+            {
+                case NetworkPrefabOverride.Hash:
+                    {
+                        if (SourceHashToOverride == 0)
+                        {
+                            if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
+                            {
+                                NetworkLog.LogWarning($"{nameof(NetworkPrefab)} {nameof(SourceHashToOverride)} is zero " +
+                                    "(entry will be ignored).");
+                            }
+                            return false;
+                        }
+
+                        break;
+                    }
+                case NetworkPrefabOverride.Prefab:
+                    {
+                        if (SourcePrefabToOverride == null)
+                        {
+                            // This is a leftover side-effect from NetworkManager's OnValidate. It's a usability
+                            // adjustment to automatically set the "Prefab" field as the source prefab when a user
+                            // swaps from the default Inspector to the override one.
+                            if (Prefab != null)
+                            {
+                                SourcePrefabToOverride = Prefab;
+                            }
+                            else if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
+                            {
+                                NetworkLog.LogWarning($"{nameof(NetworkPrefab)} {nameof(SourcePrefabToOverride)} is null (entry will be ignored).");
+                                return false;
+                            }
+                        }
+
+                        if (!SourcePrefabToOverride.TryGetComponent(out networkObject))
+                        {
+                            if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
+                            {
+                                NetworkLog.LogWarning($"{nameof(NetworkPrefab)} ({SourcePrefabToOverride.name}) " +
+                                    $"is missing a {nameof(NetworkObject)} component (entry will be ignored).");
+                            }
+                            return false;
+                        }
+
+                        break;
+                    }
+            }
+
+            // Validate target prefab override values next
+            if (OverridingTargetPrefab == null)
+            {
+                if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
+                {
+                    NetworkLog.LogWarning($"{nameof(NetworkPrefab)} {nameof(OverridingTargetPrefab)} is null!");
+                }
+                switch (Override)
+                {
+                    case NetworkPrefabOverride.Hash:
+                        {
+                            Debug.LogWarning($"{nameof(NetworkPrefab)} override entry {SourceHashToOverride} will be removed and ignored.");
+                            break;
+                        }
+                    case NetworkPrefabOverride.Prefab:
+                        {
+                            Debug.LogWarning($"{nameof(NetworkPrefab)} override entry ({SourcePrefabToOverride.name}) will be removed and ignored.");
+                            break;
+                        }
+                }
+                return false;
+            }
+            return true;
+        }
+
+        public override string ToString()
+        {
+            return $"{{SourceHash: {SourceHashToOverride}, TargetHash: {TargetPrefabGlobalObjectIdHash}}}";
+        }
     }
 }

Runtime/Configuration/NetworkPrefabs.cs

@@ -0,0 +1,297 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using UnityEngine;
+
+namespace Unity.Netcode
+{
+    /// <summary>
+    /// A class that represents the runtime aspect of network prefabs.
+    /// This class contains processed prefabs from the NetworkPrefabsList, as
+    /// well as additional modifications (additions and removals) made at runtime.
+    /// </summary>
+    [Serializable]
+    public class NetworkPrefabs
+    {
+        /// <summary>
+        /// Edit-time scripted object containing a list of NetworkPrefabs.
+        /// </summary>
+        /// <remarks>
+        /// This field can be null if no prefabs are pre-configured.
+        /// Runtime usages of <see cref="NetworkPrefabs"/> should not depend on this edit-time field for execution.
+        /// </remarks>
+        [SerializeField]
+        public List<NetworkPrefabsList> NetworkPrefabsLists = new List<NetworkPrefabsList>();
+
+        /// <summary>
+        /// This dictionary provides a quick way to check and see if a NetworkPrefab has a NetworkPrefab override.
+        /// Generated at runtime and OnValidate
+        /// </summary>
+        [NonSerialized]
+        public Dictionary<uint, NetworkPrefab> NetworkPrefabOverrideLinks = new Dictionary<uint, NetworkPrefab>();
+
+        [NonSerialized]
+        public Dictionary<uint, uint> OverrideToNetworkPrefab = new Dictionary<uint, uint>();
+
+        public IReadOnlyList<NetworkPrefab> Prefabs => m_Prefabs;
+
+        [NonSerialized]
+        private List<NetworkPrefab> m_Prefabs = new List<NetworkPrefab>();
+
+        private void AddTriggeredByNetworkPrefabList(NetworkPrefab networkPrefab)
+        {
+            if (AddPrefabRegistration(networkPrefab))
+            {
+                m_Prefabs.Add(networkPrefab);
+            }
+        }
+
+        private void RemoveTriggeredByNetworkPrefabList(NetworkPrefab networkPrefab)
+        {
+            m_Prefabs.Remove(networkPrefab);
+        }
+
+        ~NetworkPrefabs()
+        {
+            foreach (var list in NetworkPrefabsLists)
+            {
+                list.OnAdd -= AddTriggeredByNetworkPrefabList;
+                list.OnRemove -= RemoveTriggeredByNetworkPrefabList;
+            }
+        }
+
+        /// <summary>
+        /// Processes the <see cref="NetworkPrefabsList"/> if one is present for use during runtime execution,
+        /// else processes <see cref="Prefabs"/>.
+        /// </summary>
+        public void Initialize(bool warnInvalid = true)
+        {
+            if (NetworkPrefabsLists.Count != 0 && m_Prefabs.Count > 0)
+            {
+                NetworkLog.LogWarning("Runtime Network Prefabs was not empty at initialization time. Network " +
+                    "Prefab registrations made before initialization will be replaced by NetworkPrefabsList.");
+                m_Prefabs.Clear();
+            }
+
+            foreach (var list in NetworkPrefabsLists)
+            {
+                list.OnAdd += AddTriggeredByNetworkPrefabList;
+                list.OnRemove += RemoveTriggeredByNetworkPrefabList;
+            }
+
+            NetworkPrefabOverrideLinks.Clear();
+            OverrideToNetworkPrefab.Clear();
+
+            var prefabs = NetworkPrefabsLists.Count != 0 ? new List<NetworkPrefab>() : m_Prefabs;
+
+            if (NetworkPrefabsLists.Count != 0)
+            {
+                foreach (var list in NetworkPrefabsLists)
+                {
+                    foreach (var networkPrefab in list.PrefabList)
+                    {
+                        prefabs.Add(networkPrefab);
+                    }
+                }
+            }
+
+            m_Prefabs = new List<NetworkPrefab>();
+
+            List<NetworkPrefab> removeList = null;
+            if (warnInvalid)
+            {
+                removeList = new List<NetworkPrefab>();
+            }
+
+            foreach (var networkPrefab in prefabs)
+            {
+                if (AddPrefabRegistration(networkPrefab))
+                {
+                    m_Prefabs.Add(networkPrefab);
+                }
+                else
+                {
+                    removeList?.Add(networkPrefab);
+                }
+            }
+
+            // Clear out anything that is invalid or not used
+            if (removeList?.Count > 0)
+            {
+                if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
+                {
+                    var sb = new StringBuilder("Removing invalid prefabs from Network Prefab registration: ");
+                    sb.Append(string.Join(", ", removeList));
+                    NetworkLog.LogWarning(sb.ToString());
+                }
+            }
+        }
+
+        /// <summary>
+        /// Add a new NetworkPrefab instance to the list
+        /// </summary>
+        /// <remarks>
+        /// The framework does not synchronize this list between clients. Any runtime changes must be handled manually.
+        ///
+        /// Any modifications made here are not persisted. Permanent configuration changes should be done
+        /// through the <see cref="NetworkPrefabsList"/> scriptable object property.
+        /// </remarks>
+        public bool Add(NetworkPrefab networkPrefab)
+        {
+            if (AddPrefabRegistration(networkPrefab))
+            {
+                m_Prefabs.Add(networkPrefab);
+                return true;
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Remove a NetworkPrefab instance from the list
+        /// </summary>
+        /// <remarks>
+        /// The framework does not synchronize this list between clients. Any runtime changes must be handled manually.
+        ///
+        /// Any modifications made here are not persisted. Permanent configuration changes should be done
+        /// through the <see cref="NetworkPrefabsList"/> scriptable object property.
+        /// </remarks>
+        public void Remove(NetworkPrefab prefab)
+        {
+            if (prefab == null)
+            {
+                throw new ArgumentNullException(nameof(prefab));
+            }
+
+            m_Prefabs.Remove(prefab);
+            OverrideToNetworkPrefab.Remove(prefab.TargetPrefabGlobalObjectIdHash);
+            NetworkPrefabOverrideLinks.Remove(prefab.SourcePrefabGlobalObjectIdHash);
+        }
+
+        /// <summary>
+        /// Remove a NetworkPrefab instance with matching <see cref="NetworkPrefab.Prefab"/> from the list
+        /// </summary>
+        /// <remarks>
+        /// The framework does not synchronize this list between clients. Any runtime changes must be handled manually.
+        ///
+        /// Any modifications made here are not persisted. Permanent configuration changes should be done
+        /// through the <see cref="NetworkPrefabsList"/> scriptable object property.
+        /// </remarks>
+        public void Remove(GameObject prefab)
+        {
+            if (prefab == null)
+            {
+                throw new ArgumentNullException(nameof(prefab));
+            }
+
+            for (int i = 0; i < m_Prefabs.Count; i++)
+            {
+                if (m_Prefabs[i].Prefab == prefab)
+                {
+                    Remove(m_Prefabs[i]);
+                    return;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Check if the given GameObject is present as a prefab within the list
+        /// </summary>
+        /// <param name="prefab">The prefab to check</param>
+        /// <returns>Whether or not the prefab exists</returns>
+        public bool Contains(GameObject prefab)
+        {
+            for (int i = 0; i < m_Prefabs.Count; i++)
+            {
+                if (m_Prefabs[i].Prefab == prefab)
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Check if the given NetworkPrefab is present within the list
+        /// </summary>
+        /// <param name="prefab">The prefab to check</param>
+        /// <returns>Whether or not the prefab exists</returns>
+        public bool Contains(NetworkPrefab prefab)
+        {
+            for (int i = 0; i < m_Prefabs.Count; i++)
+            {
+                if (m_Prefabs[i].Equals(prefab))
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Configures <see cref="NetworkPrefabOverrideLinks"/> and <see cref="OverrideToNetworkPrefab"/> for the given <see cref="NetworkPrefab"/>
+        /// </summary>
+        private bool AddPrefabRegistration(NetworkPrefab networkPrefab)
+        {
+            if (networkPrefab == null)
+            {
+                return false;
+            }
+            // Safeguard validation check since this method is called from outside of NetworkConfig and we can't control what's passed in.
+            if (!networkPrefab.Validate())
+            {
+                return false;
+            }
+
+            uint source = networkPrefab.SourcePrefabGlobalObjectIdHash;
+            uint target = networkPrefab.TargetPrefabGlobalObjectIdHash;
+
+            // Make sure the prefab isn't already registered.
+            if (NetworkPrefabOverrideLinks.ContainsKey(source))
+            {
+                var networkObject = networkPrefab.Prefab.GetComponent<NetworkObject>();
+
+                // This should never happen, but in the case it somehow does log an error and remove the duplicate entry
+                Debug.LogError($"{nameof(NetworkPrefab)} ({networkObject.name}) has a duplicate {nameof(NetworkObject.GlobalObjectIdHash)} source entry value of: {source}!");
+                return false;
+            }
+
+            // If we don't have an override configured, registration is simple!
+            if (networkPrefab.Override == NetworkPrefabOverride.None)
+            {
+                NetworkPrefabOverrideLinks.Add(source, networkPrefab);
+                return true;
+            }
+
+            // Make sure we don't have several overrides targeting the same prefab. Apparently we don't support that... shame.
+            if (OverrideToNetworkPrefab.ContainsKey(target))
+            {
+                var networkObject = networkPrefab.Prefab.GetComponent<NetworkObject>();
+
+                // This can happen if a user tries to make several GlobalObjectIdHash values point to the same target
+                Debug.LogError($"{nameof(NetworkPrefab)} (\"{networkObject.name}\") has a duplicate {nameof(NetworkObject.GlobalObjectIdHash)} target entry value of: {target}!");
+                return false;
+            }
+
+            switch (networkPrefab.Override)
+            {
+                case NetworkPrefabOverride.Prefab:
+                    {
+                        NetworkPrefabOverrideLinks.Add(source, networkPrefab);
+                        OverrideToNetworkPrefab.Add(target, source);
+                    }
+                    break;
+                case NetworkPrefabOverride.Hash:
+                    {
+                        NetworkPrefabOverrideLinks.Add(source, networkPrefab);
+                        OverrideToNetworkPrefab.Add(target, source);
+                    }
+                    break;
+            }
+
+            return true;
+        }
+    }
+}

Runtime/Configuration/NetworkPrefabs.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 230fc75f5639e46dc91734aa67d56a3e
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Runtime/Configuration/NetworkPrefabsList.cs

@@ -0,0 +1,95 @@
+using System.Collections.Generic;
+using UnityEngine;
+using UnityEngine.Serialization;
+
+namespace Unity.Netcode
+{
+    /// <summary>
+    /// A ScriptableObject for holding a network prefabs list, which can be
+    /// shared between multiple NetworkManagers.
+    ///
+    /// When NetworkManagers hold references to this list, modifications to the
+    /// list at runtime will be picked up by all NetworkManagers that reference it.
+    /// </summary>
+    [CreateAssetMenu(fileName = "NetworkPrefabsList", menuName = "Netcode/Network Prefabs List")]
+    public class NetworkPrefabsList : ScriptableObject
+    {
+        internal delegate void OnAddDelegate(NetworkPrefab prefab);
+        internal OnAddDelegate OnAdd;
+
+        internal delegate void OnRemoveDelegate(NetworkPrefab prefab);
+        internal OnRemoveDelegate OnRemove;
+
+        [SerializeField]
+        internal bool IsDefault;
+
+        [FormerlySerializedAs("Prefabs")]
+        [SerializeField]
+        internal List<NetworkPrefab> List = new List<NetworkPrefab>();
+
+        /// <summary>
+        /// Read-only view into the prefabs list, enabling iterating and examining the list.
+        /// Actually modifying the list should be done using <see cref="Add"/>
+        /// and <see cref="Remove"/>.
+        /// </summary>
+        public IReadOnlyList<NetworkPrefab> PrefabList => List;
+
+        /// <summary>
+        /// Adds a prefab to the prefab list. Performing this here will apply the operation to all
+        /// <see cref="NetworkManager"/>s that reference this list.
+        /// </summary>
+        /// <param name="prefab"></param>
+        public void Add(NetworkPrefab prefab)
+        {
+            List.Add(prefab);
+            OnAdd?.Invoke(prefab);
+        }
+
+        /// <summary>
+        /// Removes a prefab from the prefab list. Performing this here will apply the operation to all
+        /// <see cref="NetworkManager"/>s that reference this list.
+        /// </summary>
+        /// <param name="prefab"></param>
+        public void Remove(NetworkPrefab prefab)
+        {
+            List.Remove(prefab);
+            OnRemove?.Invoke(prefab);
+        }
+
+        /// <summary>
+        /// Check if the given GameObject is present as a prefab within the list
+        /// </summary>
+        /// <param name="prefab">The prefab to check</param>
+        /// <returns>Whether or not the prefab exists</returns>
+        public bool Contains(GameObject prefab)
+        {
+            for (int i = 0; i < List.Count; i++)
+            {
+                if (List[i].Prefab == prefab)
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Check if the given NetworkPrefab is present within the list
+        /// </summary>
+        /// <param name="prefab">The prefab to check</param>
+        /// <returns>Whether or not the prefab exists</returns>
+        public bool Contains(NetworkPrefab prefab)
+        {
+            for (int i = 0; i < List.Count; i++)
+            {
+                if (List[i].Equals(prefab))
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+    }
+}

Runtime/Configuration/NetworkPrefabsList.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: e651dbb3fbac04af2b8f5abf007ddc23
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Runtime/Core/NetworkBehaviour.cs

@@ -314,18 +314,18 @@ namespace Unity.Netcode
         /// <summary>
         /// Gets if we are executing as server
         /// </summary>
-        protected bool IsServer { get; private set; }
+        public bool IsServer { get; private set; }
 
         /// <summary>
         /// Gets if we are executing as client
         /// </summary>
-        protected bool IsClient { get; private set; }
+        public bool IsClient { get; private set; }
 
 
         /// <summary>
         /// Gets if we are executing as Host, I.E Server and Client
         /// </summary>
-        protected bool IsHost { get; private set; }
+        public bool IsHost { get; private set; }
 
         /// <summary>
         /// Gets Whether or not the object has a owner
@@ -570,11 +570,11 @@ namespace Unity.Netcode
             if (list == null)
             {
                 list = new List<FieldInfo>();
-                list.AddRange(type.GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance));
+                list.AddRange(type.GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.DeclaredOnly));
             }
             else
             {
-                list.AddRange(type.GetFields(BindingFlags.NonPublic | BindingFlags.Instance));
+                list.AddRange(type.GetFields(BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.DeclaredOnly));
             }
 
             if (type.BaseType != null && type.BaseType != typeof(NetworkBehaviour))

Runtime/Core/NetworkBehaviourUpdater.cs

@@ -72,6 +72,23 @@ namespace Unity.Netcode
                         }
                     }
                 }
+
+                foreach (var dirtyObj in m_DirtyNetworkObjects)
+                {
+                    for (int k = 0; k < dirtyObj.ChildNetworkBehaviours.Count; k++)
+                    {
+                        var behaviour = dirtyObj.ChildNetworkBehaviours[k];
+                        for (int i = 0; i < behaviour.NetworkVariableFields.Count; i++)
+                        {
+                            if (behaviour.NetworkVariableFields[i].IsDirty() &&
+                                !behaviour.NetworkVariableIndexesToResetSet.Contains(i))
+                            {
+                                behaviour.NetworkVariableIndexesToResetSet.Add(i);
+                                behaviour.NetworkVariableIndexesToReset.Add(i);
+                            }
+                        }
+                    }
+                }
                 // Now, reset all the no-longer-dirty variables
                 foreach (var dirtyobj in m_DirtyNetworkObjects)
                 {

Runtime/Core/NetworkManager.cs

@@ -67,6 +67,9 @@ namespace Unity.Netcode
 
         internal Dictionary<ulong, ConnectionApprovalResponse> ClientsToApprove = new Dictionary<ulong, ConnectionApprovalResponse>();
 
+        // Stores the objects that need to be shown at end-of-frame
+        internal Dictionary<ulong, List<NetworkObject>> ObjectsToShowToClient = new Dictionary<ulong, List<NetworkObject>>();
+
         /// <summary>
         /// The <see cref="NetworkPrefabHandler"/> instance created after starting the <see cref="NetworkManager"/>
         /// </summary>
@@ -140,15 +143,55 @@ namespace Unity.Netcode
 
             public bool OnVerifyCanReceive(ulong senderId, Type messageType, FastBufferReader messageContent, ref NetworkContext context)
             {
-                if (m_NetworkManager.PendingClients.TryGetValue(senderId, out PendingClient client) &&
-                    (client.ConnectionState == PendingClient.State.PendingApproval || (client.ConnectionState == PendingClient.State.PendingConnection && messageType != typeof(ConnectionRequestMessage))))
+                if (m_NetworkManager.IsServer)
                 {
-                    if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+                    if (messageType == typeof(ConnectionApprovedMessage))
                     {
-                        NetworkLog.LogWarning($"Message received from {nameof(senderId)}={senderId} before it has been accepted");
+                        if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+                        {
+                            NetworkLog.LogError($"A {nameof(ConnectionApprovedMessage)} was received from a client on the server side. This should not happen. Please report this to the Netcode for GameObjects team at https://github.com/Unity-Technologies/com.unity.netcode.gameobjects/issues and include the following data: Message Size: {messageContent.Length}. Message Content: {MessagingSystem.ByteArrayToString(messageContent.ToArray(), 0, messageContent.Length)}");
+                        }
+                        return false;
+                    }
+                    if (m_NetworkManager.PendingClients.TryGetValue(senderId, out PendingClient client) &&
+                                     (client.ConnectionState == PendingClient.State.PendingApproval || (client.ConnectionState == PendingClient.State.PendingConnection && messageType != typeof(ConnectionRequestMessage))))
+                    {
+                        if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+                        {
+                            NetworkLog.LogWarning($"Message received from {nameof(senderId)}={senderId} before it has been accepted");
+                        }
+
+                        return false;
                     }
 
-                    return false;
+                    if (m_NetworkManager.ConnectedClients.TryGetValue(senderId, out NetworkClient connectedClient) && messageType == typeof(ConnectionRequestMessage))
+                    {
+                        if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+                        {
+                            NetworkLog.LogError($"A {nameof(ConnectionRequestMessage)} was received from a client when the connection has already been established. This should not happen. Please report this to the Netcode for GameObjects team at https://github.com/Unity-Technologies/com.unity.netcode.gameobjects/issues and include the following data: Message Size: {messageContent.Length}. Message Content: {MessagingSystem.ByteArrayToString(messageContent.ToArray(), 0, messageContent.Length)}");
+                        }
+
+                        return false;
+                    }
+                }
+                else
+                {
+                    if (messageType == typeof(ConnectionRequestMessage))
+                    {
+                        if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+                        {
+                            NetworkLog.LogError($"A {nameof(ConnectionRequestMessage)} was received from the server on the client side. This should not happen. Please report this to the Netcode for GameObjects team at https://github.com/Unity-Technologies/com.unity.netcode.gameobjects/issues and include the following data: Message Size: {messageContent.Length}. Message Content: {MessagingSystem.ByteArrayToString(messageContent.ToArray(), 0, messageContent.Length)}");
+                        }
+                        return false;
+                    }
+                    if (m_NetworkManager.IsConnectedClient && messageType == typeof(ConnectionApprovedMessage))
+                    {
+                        if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+                        {
+                            NetworkLog.LogError($"A {nameof(ConnectionApprovedMessage)} was received from the server when the connection has already been established. This should not happen. Please report this to the Netcode for GameObjects team at https://github.com/Unity-Technologies/com.unity.netcode.gameobjects/issues and include the following data: Message Size: {messageContent.Length}. Message Content: {MessagingSystem.ByteArrayToString(messageContent.ToArray(), 0, messageContent.Length)}");
+                        }
+                        return false;
+                    }
                 }
 
                 return !m_NetworkManager.m_StopProcessingMessages;
@@ -195,14 +238,14 @@ namespace Unity.Netcode
         {
             if (gameObject.TryGetComponent<NetworkObject>(out var networkObject))
             {
-                if (NetworkConfig.NetworkPrefabOverrideLinks.ContainsKey(networkObject.GlobalObjectIdHash))
+                if (NetworkConfig.Prefabs.NetworkPrefabOverrideLinks.ContainsKey(networkObject.GlobalObjectIdHash))
                 {
-                    switch (NetworkConfig.NetworkPrefabOverrideLinks[networkObject.GlobalObjectIdHash].Override)
+                    switch (NetworkConfig.Prefabs.NetworkPrefabOverrideLinks[networkObject.GlobalObjectIdHash].Override)
                     {
                         case NetworkPrefabOverride.Hash:
                         case NetworkPrefabOverride.Prefab:
                             {
-                                return NetworkConfig.NetworkPrefabOverrideLinks[networkObject.GlobalObjectIdHash].OverridingTargetPrefab;
+                                return NetworkConfig.Prefabs.NetworkPrefabOverrideLinks[networkObject.GlobalObjectIdHash].OverridingTargetPrefab;
                             }
                     }
                 }
@@ -280,7 +323,7 @@ namespace Unity.Netcode
         /// </summary>
         public ulong LocalClientId
         {
-            get => IsServer ? NetworkConfig.NetworkTransport.ServerClientId : m_LocalClientId;
+            get => m_LocalClientId;
             internal set => m_LocalClientId = value;
         }
 
@@ -508,6 +551,19 @@ namespace Unity.Netcode
 
         internal static event Action OnSingletonReady;
 
+#if UNITY_EDITOR
+        internal delegate void ResetNetworkManagerDelegate(NetworkManager manager);
+
+        internal static ResetNetworkManagerDelegate OnNetworkManagerReset;
+#endif
+
+        private void Reset()
+        {
+#if UNITY_EDITOR
+            OnNetworkManagerReset?.Invoke(this);
+#endif
+        }
+
 #if UNITY_EDITOR
         internal void OnValidate()
         {
@@ -533,72 +589,38 @@ namespace Unity.Netcode
             }
 
             // During OnValidate we will always clear out NetworkPrefabOverrideLinks and rebuild it
-            NetworkConfig.NetworkPrefabOverrideLinks.Clear();
+            NetworkConfig.Prefabs.NetworkPrefabOverrideLinks.Clear();
 
+            var prefabs = NetworkConfig.Prefabs.Prefabs;
             // Check network prefabs and assign to dictionary for quick look up
-            for (int i = 0; i < NetworkConfig.NetworkPrefabs.Count; i++)
+            for (int i = 0; i < prefabs.Count; i++)
             {
-                var networkPrefab = NetworkConfig.NetworkPrefabs[i];
+                var networkPrefab = prefabs[i];
                 var networkPrefabGo = networkPrefab?.Prefab;
-                if (networkPrefabGo != null)
+                if (networkPrefabGo == null)
                 {
-                    if (!networkPrefabGo.TryGetComponent<NetworkObject>(out var networkObject))
+                    continue;
+                }
+
+                var networkObject = networkPrefabGo.GetComponent<NetworkObject>();
+                if (networkObject == null)
+                {
+                    if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+                    {
+                        NetworkLog.LogError($"Cannot register {PrefabDebugHelper(networkPrefab)}, it does not have a {nameof(NetworkObject)} component at its root");
+                    }
+
+                    continue;
+                }
+
+                {
+                    var childNetworkObjects = new List<NetworkObject>();
+                    networkPrefabGo.GetComponentsInChildren(true, childNetworkObjects);
+                    if (childNetworkObjects.Count > 1) // total count = 1 root NetworkObject + n child NetworkObjects
                     {
                         if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
                         {
-                            NetworkLog.LogError($"Cannot register {PrefabDebugHelper(networkPrefab)}, it does not have a {nameof(NetworkObject)} component at its root");
-                        }
-                    }
-                    else
-                    {
-                        {
-                            var childNetworkObjects = new List<NetworkObject>();
-                            networkPrefabGo.GetComponentsInChildren(true, childNetworkObjects);
-                            if (childNetworkObjects.Count > 1) // total count = 1 root NetworkObject + n child NetworkObjects
-                            {
-                                if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
-                                {
-                                    NetworkLog.LogWarning($"{PrefabDebugHelper(networkPrefab)} has child {nameof(NetworkObject)}(s) but they will not be spawned across the network (unsupported {nameof(NetworkPrefab)} setup)");
-                                }
-                            }
-                        }
-
-                        // Default to the standard NetworkPrefab.Prefab's NetworkObject first
-                        var globalObjectIdHash = networkObject.GlobalObjectIdHash;
-
-                        // Now check to see if it has an override
-                        switch (networkPrefab.Override)
-                        {
-                            case NetworkPrefabOverride.Prefab:
-                                {
-                                    if (NetworkConfig.NetworkPrefabs[i].SourcePrefabToOverride == null &&
-                                        NetworkConfig.NetworkPrefabs[i].Prefab != null)
-                                    {
-                                        if (networkPrefab.SourcePrefabToOverride == null)
-                                        {
-                                            networkPrefab.SourcePrefabToOverride = networkPrefabGo;
-                                        }
-
-                                        globalObjectIdHash = networkPrefab.SourcePrefabToOverride.GetComponent<NetworkObject>().GlobalObjectIdHash;
-                                    }
-
-                                    break;
-                                }
-                            case NetworkPrefabOverride.Hash:
-                                globalObjectIdHash = networkPrefab.SourceHashToOverride;
-                                break;
-                        }
-
-                        // Add to the NetworkPrefabOverrideLinks or handle a new (blank) entries
-                        if (!NetworkConfig.NetworkPrefabOverrideLinks.ContainsKey(globalObjectIdHash))
-                        {
-                            NetworkConfig.NetworkPrefabOverrideLinks.Add(globalObjectIdHash, networkPrefab);
-                        }
-                        else
-                        {
-                            // Duplicate entries can happen when adding a new entry into a list of existing entries
-                            // Either this is user error or a new entry, either case we replace it with a new, blank, NetworkPrefab under this condition
-                            NetworkConfig.NetworkPrefabs[i] = new NetworkPrefab();
+                            NetworkLog.LogWarning($"{PrefabDebugHelper(networkPrefab)} has child {nameof(NetworkObject)}(s) but they will not be spawned across the network (unsupported {nameof(NetworkPrefab)} setup)");
                         }
                     }
                 }
@@ -640,22 +662,9 @@ namespace Unity.Netcode
             }
 
             var networkPrefab = new NetworkPrefab { Prefab = prefab };
-            NetworkConfig.NetworkPrefabs.Add(networkPrefab);
-            if (IsListening)
+            bool added = NetworkConfig.Prefabs.Add(networkPrefab);
+            if (IsListening && added)
             {
-                var sourcePrefabGlobalObjectIdHash = (uint)0;
-                var targetPrefabGlobalObjectIdHash = (uint)0;
-                if (!ShouldAddPrefab(networkPrefab, out sourcePrefabGlobalObjectIdHash, out targetPrefabGlobalObjectIdHash))
-                {
-                    NetworkConfig.NetworkPrefabs.Remove(networkPrefab);
-                    return;
-                }
-
-                if (!AddPrefabRegistration(networkPrefab, sourcePrefabGlobalObjectIdHash, targetPrefabGlobalObjectIdHash))
-                {
-                    NetworkConfig.NetworkPrefabs.Remove(networkPrefab);
-                    return;
-                }
                 DeferredMessageManager.ProcessTriggers(IDeferredMessageManager.TriggerType.OnAddPrefab, networkObject.GlobalObjectIdHash);
             }
         }
@@ -678,221 +687,14 @@ namespace Unity.Netcode
             }
 
             var globalObjectIdHash = prefab.GetComponent<NetworkObject>().GlobalObjectIdHash;
-            for (var i = 0; i < NetworkConfig.NetworkPrefabs.Count; ++i)
-            {
-                if (NetworkConfig.NetworkPrefabs[i].Prefab.GetComponent<NetworkObject>().GlobalObjectIdHash == globalObjectIdHash)
-                {
-                    NetworkConfig.NetworkPrefabs.RemoveAt(i);
-                    break;
-                }
-            }
+            NetworkConfig.Prefabs.Remove(prefab);
             if (PrefabHandler.ContainsHandler(globalObjectIdHash))
             {
                 PrefabHandler.RemoveHandler(globalObjectIdHash);
             }
-            if (NetworkConfig.NetworkPrefabOverrideLinks.TryGetValue(globalObjectIdHash, out var targetPrefab))
-            {
-                NetworkConfig.NetworkPrefabOverrideLinks.Remove(globalObjectIdHash);
-                var targetHash = targetPrefab.Prefab.GetComponent<NetworkObject>().GlobalObjectIdHash;
-                if (NetworkConfig.OverrideToNetworkPrefab.ContainsKey(targetHash))
-                {
-                    NetworkConfig.OverrideToNetworkPrefab.Remove(targetHash);
-                }
-            }
         }
 
-        private bool ShouldAddPrefab(NetworkPrefab networkPrefab, out uint sourcePrefabGlobalObjectIdHash, out uint targetPrefabGlobalObjectIdHash, int index = -1)
-        {
-            sourcePrefabGlobalObjectIdHash = 0;
-            targetPrefabGlobalObjectIdHash = 0;
-            var networkObject = (NetworkObject)null;
-            if (networkPrefab == null || (networkPrefab.Prefab == null && networkPrefab.Override == NetworkPrefabOverride.None))
-            {
-                if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
-                {
-                    NetworkLog.LogWarning(
-                        $"{nameof(NetworkPrefab)} cannot be null ({nameof(NetworkPrefab)} at index: {index})");
-                }
-                return false;
-            }
-            else if (networkPrefab.Override == NetworkPrefabOverride.None)
-            {
-                if (!networkPrefab.Prefab.TryGetComponent(out networkObject))
-                {
-                    if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
-                    {
-                        NetworkLog.LogWarning($"{PrefabDebugHelper(networkPrefab)} is missing " +
-                                              $"a {nameof(NetworkObject)} component (entry will be ignored).");
-                    }
-                    return false;
-                }
-
-                // Otherwise get the GlobalObjectIdHash value
-                sourcePrefabGlobalObjectIdHash = networkObject.GlobalObjectIdHash;
-            }
-            else // Validate Overrides
-            {
-                // Validate source prefab override values first
-                switch (networkPrefab.Override)
-                {
-                    case NetworkPrefabOverride.Hash:
-                        {
-                            if (networkPrefab.SourceHashToOverride == 0)
-                            {
-                                if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
-                                {
-                                    NetworkLog.LogWarning($"{nameof(NetworkPrefab)} {nameof(NetworkPrefab.SourceHashToOverride)} is zero " +
-                                                          "(entry will be ignored).");
-                                }
-                                return false;
-                            }
-                            sourcePrefabGlobalObjectIdHash = networkPrefab.SourceHashToOverride;
-                            break;
-                        }
-                    case NetworkPrefabOverride.Prefab:
-                        {
-                            if (networkPrefab.SourcePrefabToOverride == null)
-                            {
-                                if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
-                                {
-                                    NetworkLog.LogWarning($"{nameof(NetworkPrefab)} {nameof(NetworkPrefab.SourcePrefabToOverride)} is null (entry will be ignored).");
-                                }
-
-                                Debug.LogWarning($"{nameof(NetworkPrefab)} override entry {networkPrefab.SourceHashToOverride} will be removed and ignored.");
-                                return false;
-                            }
-                            else
-                            {
-                                if (!networkPrefab.SourcePrefabToOverride.TryGetComponent(out networkObject))
-                                {
-                                    if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
-                                    {
-                                        NetworkLog.LogWarning($"{nameof(NetworkPrefab)} ({networkPrefab.SourcePrefabToOverride.name}) " +
-                                                              $"is missing a {nameof(NetworkObject)} component (entry will be ignored).");
-                                    }
-
-                                    Debug.LogWarning($"{nameof(NetworkPrefab)} override entry (\"{networkPrefab.SourcePrefabToOverride.name}\") will be removed and ignored.");
-                                    return false;
-                                }
-
-                                sourcePrefabGlobalObjectIdHash = networkObject.GlobalObjectIdHash;
-                            }
-                            break;
-                        }
-                }
-
-                // Validate target prefab override values next
-                if (networkPrefab.OverridingTargetPrefab == null)
-                {
-                    if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
-                    {
-                        NetworkLog.LogWarning($"{nameof(NetworkPrefab)} {nameof(NetworkPrefab.OverridingTargetPrefab)} is null!");
-                    }
-                    switch (networkPrefab.Override)
-                    {
-                        case NetworkPrefabOverride.Hash:
-                            {
-                                Debug.LogWarning($"{nameof(NetworkPrefab)} override entry {networkPrefab.SourceHashToOverride} will be removed and ignored.");
-                                break;
-                            }
-                        case NetworkPrefabOverride.Prefab:
-                            {
-                                Debug.LogWarning($"{nameof(NetworkPrefab)} override entry ({networkPrefab.SourcePrefabToOverride.name}) will be removed and ignored.");
-                                break;
-                            }
-                    }
-                    return false;
-                }
-                else
-                {
-                    targetPrefabGlobalObjectIdHash = networkPrefab.OverridingTargetPrefab.GetComponent<NetworkObject>().GlobalObjectIdHash;
-                }
-            }
-            return true;
-        }
-
-        internal bool AddPrefabRegistration(NetworkPrefab networkPrefab, uint sourcePrefabGlobalObjectIdHash, uint targetPrefabGlobalObjectIdHash)
-        {
-            // Assign the appropriate GlobalObjectIdHash to the appropriate NetworkPrefab
-            if (!NetworkConfig.NetworkPrefabOverrideLinks.ContainsKey(sourcePrefabGlobalObjectIdHash))
-            {
-                if (networkPrefab.Override == NetworkPrefabOverride.None)
-                {
-                    NetworkConfig.NetworkPrefabOverrideLinks.Add(sourcePrefabGlobalObjectIdHash, networkPrefab);
-                }
-                else
-                {
-                    if (!NetworkConfig.OverrideToNetworkPrefab.ContainsKey(targetPrefabGlobalObjectIdHash))
-                    {
-                        switch (networkPrefab.Override)
-                        {
-                            case NetworkPrefabOverride.Prefab:
-                                {
-                                    NetworkConfig.NetworkPrefabOverrideLinks.Add(sourcePrefabGlobalObjectIdHash, networkPrefab);
-                                    NetworkConfig.OverrideToNetworkPrefab.Add(targetPrefabGlobalObjectIdHash, sourcePrefabGlobalObjectIdHash);
-                                }
-                                break;
-                            case NetworkPrefabOverride.Hash:
-                                {
-                                    NetworkConfig.NetworkPrefabOverrideLinks.Add(sourcePrefabGlobalObjectIdHash, networkPrefab);
-                                    NetworkConfig.OverrideToNetworkPrefab.Add(targetPrefabGlobalObjectIdHash, sourcePrefabGlobalObjectIdHash);
-                                }
-                                break;
-                        }
-                    }
-                    else
-                    {
-                        var networkObject = networkPrefab.Prefab.GetComponent<NetworkObject>();
-                        // This can happen if a user tries to make several GlobalObjectIdHash values point to the same target
-                        Debug.LogError($"{nameof(NetworkPrefab)} (\"{networkObject.name}\") has a duplicate {nameof(NetworkObject.GlobalObjectIdHash)} target entry value of: {targetPrefabGlobalObjectIdHash}! Removing entry from list!");
-                        return false;
-                    }
-                }
-            }
-            else
-            {
-                var networkObject = networkPrefab.Prefab.GetComponent<NetworkObject>();
-                // This should never happen, but in the case it somehow does log an error and remove the duplicate entry
-                Debug.LogError($"{nameof(NetworkPrefab)} ({networkObject.name}) has a duplicate {nameof(NetworkObject.GlobalObjectIdHash)} source entry value of: {sourcePrefabGlobalObjectIdHash}! Removing entry from list!");
-                return false;
-            }
-            return true;
-        }
-
-        private void InitializePrefabs(int startIdx = 0)
-        {
-            // This is used to remove entries not needed or invalid
-            var removeEmptyPrefabs = new List<int>();
-
-            // Build the NetworkPrefabOverrideLinks dictionary
-            for (int i = startIdx; i < NetworkConfig.NetworkPrefabs.Count; i++)
-            {
-                var sourcePrefabGlobalObjectIdHash = (uint)0;
-                var targetPrefabGlobalObjectIdHash = (uint)0;
-                if (!ShouldAddPrefab(NetworkConfig.NetworkPrefabs[i], out sourcePrefabGlobalObjectIdHash, out targetPrefabGlobalObjectIdHash, i))
-                {
-                    removeEmptyPrefabs.Add(i);
-                    continue;
-                }
-
-                if (!AddPrefabRegistration(NetworkConfig.NetworkPrefabs[i], sourcePrefabGlobalObjectIdHash, targetPrefabGlobalObjectIdHash))
-                {
-                    removeEmptyPrefabs.Add(i);
-                    continue;
-                }
-            }
-
-            // Clear out anything that is invalid or not used (for invalid entries we already logged warnings to the user earlier)
-            // Iterate backwards so indices don't shift as we remove
-            for (int i = removeEmptyPrefabs.Count - 1; i >= 0; i--)
-            {
-                NetworkConfig.NetworkPrefabs.RemoveAt(removeEmptyPrefabs[i]);
-            }
-
-            removeEmptyPrefabs.Clear();
-        }
-
-        private void Initialize(bool server)
+        internal void Initialize(bool server)
         {
             // Don't allow the user to start a network session if the NetworkManager is
             // still parented under another GameObject
@@ -982,11 +784,7 @@ namespace Unity.Netcode
 
             this.RegisterNetworkUpdate(NetworkUpdateStage.PreUpdate);
 
-            // Always clear our prefab override links before building
-            NetworkConfig.NetworkPrefabOverrideLinks.Clear();
-            NetworkConfig.OverrideToNetworkPrefab.Clear();
-
-            InitializePrefabs();
+            NetworkConfig.InitializePrefabs();
 
             // If we have a player prefab, then we need to verify it is in the list of NetworkPrefabOverrideLinks for client side spawning.
             if (NetworkConfig.PlayerPrefab != null)
@@ -994,15 +792,11 @@ namespace Unity.Netcode
                 if (NetworkConfig.PlayerPrefab.TryGetComponent<NetworkObject>(out var playerPrefabNetworkObject))
                 {
                     //In the event there is no NetworkPrefab entry (i.e. no override for default player prefab)
-                    if (!NetworkConfig.NetworkPrefabOverrideLinks.ContainsKey(playerPrefabNetworkObject
+                    if (!NetworkConfig.Prefabs.NetworkPrefabOverrideLinks.ContainsKey(playerPrefabNetworkObject
                         .GlobalObjectIdHash))
                     {
                         //Then add a new entry for the player prefab
-                        var playerNetworkPrefab = new NetworkPrefab();
-                        playerNetworkPrefab.Prefab = NetworkConfig.PlayerPrefab;
-                        NetworkConfig.NetworkPrefabs.Insert(0, playerNetworkPrefab);
-                        NetworkConfig.NetworkPrefabOverrideLinks.Add(playerPrefabNetworkObject.GlobalObjectIdHash,
-                            playerNetworkPrefab);
+                        AddNetworkPrefab(NetworkConfig.PlayerPrefab);
                     }
                 }
                 else
@@ -1048,6 +842,7 @@ namespace Unity.Netcode
             IsServer = true;
             IsClient = false;
             IsListening = true;
+            LocalClientId = ServerClientId;
 
             try
             {
@@ -1282,6 +1077,8 @@ namespace Unity.Netcode
 
         private void Awake()
         {
+            NetworkConfig?.InitializePrefabs();
+
             UnityEngine.SceneManagement.SceneManager.sceneUnloaded += OnSceneUnloaded;
         }
 
@@ -1663,6 +1460,17 @@ namespace Unity.Netcode
             // Do NetworkVariable updates
             BehaviourUpdater.NetworkBehaviourUpdate(this);
 
+            // Handle NetworkObjects to show
+            foreach (var client in ObjectsToShowToClient)
+            {
+                ulong clientId = client.Key;
+                foreach (var networkObject in client.Value)
+                {
+                    SpawnManager.SendSpawnCallForObject(clientId, networkObject);
+                }
+            }
+            ObjectsToShowToClient.Clear();
+
             int timeSyncFrequencyTicks = (int)(k_TimeSyncFrequency * NetworkConfig.TickRate);
             if (IsServer && NetworkTickSystem.ServerTime.Tick % timeSyncFrequencyTicks == 0)
             {
@@ -2082,7 +1890,12 @@ namespace Unity.Netcode
                             }
                             else
                             {
-                                Destroy(playerObject.gameObject);
+                                // Call despawn to assure NetworkBehaviour.OnNetworkDespawn is invoked
+                                // on the server-side (when the client side disconnected).
+                                // This prevents the issue (when just destroying the GameObject) where
+                                // any NetworkBehaviour component(s) destroyed before the NetworkObject
+                                // would not have OnNetworkDespawn invoked.
+                                SpawnManager.DespawnObject(playerObject, true);
                             }
                         }
                         else
@@ -2334,5 +2147,37 @@ namespace Unity.Netcode
                 NetworkMetrics.TrackObjectSpawnSent(clientPair.Key, ConnectedClients[clientId].PlayerObject, size);
             }
         }
+
+        internal void MarkObjectForShowingTo(NetworkObject networkObject, ulong clientId)
+        {
+            if (!ObjectsToShowToClient.ContainsKey(clientId))
+            {
+                ObjectsToShowToClient.Add(clientId, new List<NetworkObject>());
+            }
+            ObjectsToShowToClient[clientId].Add(networkObject);
+        }
+
+        // returns whether any matching objects would have become visible and were returned to hidden state
+        internal bool RemoveObjectFromShowingTo(NetworkObject networkObject, ulong clientId)
+        {
+            var ret = false;
+            if (!ObjectsToShowToClient.ContainsKey(clientId))
+            {
+                return false;
+            }
+
+            // probably overkill, but deals with multiple entries
+            while (ObjectsToShowToClient[clientId].Contains(networkObject))
+            {
+                Debug.LogWarning(
+                    "Object was shown and hidden from the same client in the same Network frame. As a result, the client will _not_ receive a NetworkSpawn");
+                ObjectsToShowToClient[clientId].Remove(networkObject);
+                ret = true;
+            }
+
+            networkObject.Observers.Remove(clientId);
+
+            return ret;
+        }
     }
 }

Runtime/Core/NetworkObject.cs

@@ -265,9 +265,8 @@ namespace Unity.Netcode
                 throw new VisibilityChangeException("The object is already visible");
             }
 
+            NetworkManager.MarkObjectForShowingTo(this, clientId);
             Observers.Add(clientId);
-
-            NetworkManager.SpawnManager.SendSpawnCallForObject(clientId, this);
         }
 
 
@@ -351,26 +350,28 @@ namespace Unity.Netcode
                 throw new NotServerException("Only server can change visibility");
             }
 
-            if (!Observers.Contains(clientId))
-            {
-                throw new VisibilityChangeException("The object is already hidden");
-            }
-
             if (clientId == NetworkManager.ServerClientId)
             {
                 throw new VisibilityChangeException("Cannot hide an object from the server");
             }
 
-            Observers.Remove(clientId);
-
-            var message = new DestroyObjectMessage
+            if (!NetworkManager.RemoveObjectFromShowingTo(this, clientId))
             {
-                NetworkObjectId = NetworkObjectId,
-                DestroyGameObject = !IsSceneObject.Value
-            };
-            // Send destroy call
-            var size = NetworkManager.SendMessage(ref message, NetworkDelivery.ReliableSequenced, clientId);
-            NetworkManager.NetworkMetrics.TrackObjectDestroySent(clientId, this, size);
+                if (!Observers.Contains(clientId))
+                {
+                    throw new VisibilityChangeException("The object is already hidden");
+                }
+                Observers.Remove(clientId);
+
+                var message = new DestroyObjectMessage
+                {
+                    NetworkObjectId = NetworkObjectId,
+                    DestroyGameObject = !IsSceneObject.Value
+                };
+                // Send destroy call
+                var size = NetworkManager.SendMessage(ref message, NetworkDelivery.ReliableSequenced, clientId);
+                NetworkManager.NetworkMetrics.TrackObjectDestroySent(clientId, this, size);
+            }
         }
 
         /// <summary>
@@ -1454,9 +1455,9 @@ namespace Unity.Netcode
                     var globalObjectIdHash = NetworkManager.PrefabHandler.GetSourceGlobalObjectIdHash(GlobalObjectIdHash);
                     return globalObjectIdHash == 0 ? GlobalObjectIdHash : globalObjectIdHash;
                 }
-                else if (NetworkManager.NetworkConfig.OverrideToNetworkPrefab.ContainsKey(GlobalObjectIdHash))
+                if (NetworkManager.NetworkConfig.Prefabs.OverrideToNetworkPrefab.TryGetValue(GlobalObjectIdHash, out uint hash))
                 {
-                    return NetworkManager.NetworkConfig.OverrideToNetworkPrefab[GlobalObjectIdHash];
+                    return hash;
                 }
             }
 

Runtime/Messaging/BatchHeader.cs

@@ -5,9 +5,26 @@ namespace Unity.Netcode
     /// </summary>
     internal struct BatchHeader : INetworkSerializeByMemcpy
     {
+        internal const ushort MagicValue = 0x1160;
+        /// <summary>
+        /// A magic number to detect corrupt messages.
+        /// Always set to k_MagicValue
+        /// </summary>
+        public ushort Magic;
+
+        /// <summary>
+        /// Total number of bytes in the batch.
+        /// </summary>
+        public int BatchSize;
+
+        /// <summary>
+        /// Hash of the message to detect corrupt messages.
+        /// </summary>
+        public ulong BatchHash;
+
         /// <summary>
         /// Total number of messages in the batch.
         /// </summary>
-        public ushort BatchSize;
+        public ushort BatchCount;
     }
 }

Runtime/Messaging/Messages/NetworkVariableDeltaMessage.cs

@@ -64,6 +64,16 @@ namespace Unity.Netcode
                     shouldWrite = false;
                 }
 
+                // The object containing the behaviour we're about to process is about to be shown to this client
+                // As a result, the client will get the fully serialized NetworkVariable and would be confused by
+                // an extraneous delta
+                if (NetworkBehaviour.NetworkManager.ObjectsToShowToClient.ContainsKey(TargetClientId) &&
+                    NetworkBehaviour.NetworkManager.ObjectsToShowToClient[TargetClientId]
+                    .Contains(NetworkBehaviour.NetworkObject))
+                {
+                    shouldWrite = false;
+                }
+
                 if (NetworkBehaviour.NetworkManager.NetworkConfig.EnsureNetworkVariableLengthSafety)
                 {
                     if (!shouldWrite)
@@ -96,12 +106,6 @@ namespace Unity.Netcode
                         networkVariable.WriteDelta(writer);
                     }
 
-                    if (!NetworkBehaviour.NetworkVariableIndexesToResetSet.Contains(i))
-                    {
-                        NetworkBehaviour.NetworkVariableIndexesToResetSet.Add(i);
-                        NetworkBehaviour.NetworkVariableIndexesToReset.Add(i);
-                    }
-
                     NetworkBehaviour.NetworkManager.NetworkMetrics.TrackNetworkVariableDeltaSent(
                         TargetClientId,
                         NetworkBehaviour.NetworkObject,

Runtime/Messaging/MessagingSystem.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Runtime.CompilerServices;
+using System.Text;
 using Unity.Collections;
 using Unity.Collections.LowLevel.Unsafe;
 using UnityEngine;
@@ -41,7 +42,7 @@ namespace Unity.Netcode
             {
                 Writer = new FastBufferWriter(writerSize, writerAllocator, maxWriterSize);
                 NetworkDelivery = delivery;
-                BatchHeader = default;
+                BatchHeader = new BatchHeader { Magic = BatchHeader.MagicValue };
             }
         }
 
@@ -204,6 +205,17 @@ namespace Unity.Netcode
             return m_LocalVersions[messageType];
         }
 
+        internal static string ByteArrayToString(byte[] ba, int offset, int count)
+        {
+            var hex = new StringBuilder(ba.Length * 2);
+            for (int i = offset; i < offset + count; ++i)
+            {
+                hex.AppendFormat("{0:x2} ", ba[i]);
+            }
+
+            return hex.ToString();
+        }
+
         internal void HandleIncomingData(ulong clientId, ArraySegment<byte> data, float receiveTime)
         {
             unsafe
@@ -214,18 +226,38 @@ namespace Unity.Netcode
                         new FastBufferReader(nativeData + data.Offset, Allocator.None, data.Count);
                     if (!batchReader.TryBeginRead(sizeof(BatchHeader)))
                     {
-                        NetworkLog.LogWarning("Received a packet too small to contain a BatchHeader. Ignoring it.");
+                        NetworkLog.LogError("Received a packet too small to contain a BatchHeader. Ignoring it.");
                         return;
                     }
 
                     batchReader.ReadValue(out BatchHeader batchHeader);
 
-                    for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
+                    if (batchHeader.Magic != BatchHeader.MagicValue)
                     {
-                        m_Hooks[hookIdx].OnBeforeReceiveBatch(clientId, batchHeader.BatchSize, batchReader.Length);
+                        NetworkLog.LogError($"Received a packet with an invalid Magic Value. Please report this to the Netcode for GameObjects team at https://github.com/Unity-Technologies/com.unity.netcode.gameobjects/issues and include the following data: Offset: {data.Offset}, Size: {data.Count}, Full receive array: {ByteArrayToString(data.Array, 0, data.Array.Length)}");
+                        return;
                     }
 
-                    for (var messageIdx = 0; messageIdx < batchHeader.BatchSize; ++messageIdx)
+                    if (batchHeader.BatchSize != data.Count)
+                    {
+                        NetworkLog.LogError($"Received a packet with an invalid Batch Size Value. Please report this to the Netcode for GameObjects team at https://github.com/Unity-Technologies/com.unity.netcode.gameobjects/issues and include the following data: Offset: {data.Offset}, Size: {data.Count}, Expected Size: {batchHeader.BatchSize}, Full receive array: {ByteArrayToString(data.Array, 0, data.Array.Length)}");
+                        return;
+                    }
+
+                    var hash = XXHash.Hash64(batchReader.GetUnsafePtrAtCurrentPosition(), batchReader.Length - batchReader.Position);
+
+                    if (hash != batchHeader.BatchHash)
+                    {
+                        NetworkLog.LogError($"Received a packet with an invalid Hash Value. Please report this to the Netcode for GameObjects team at https://github.com/Unity-Technologies/com.unity.netcode.gameobjects/issues and include the following data: Received Hash: {batchHeader.BatchHash}, Calculated Hash: {hash}, Offset: {data.Offset}, Size: {data.Count}, Full receive array: {ByteArrayToString(data.Array, 0, data.Array.Length)}");
+                        return;
+                    }
+
+                    for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
+                    {
+                        m_Hooks[hookIdx].OnBeforeReceiveBatch(clientId, batchHeader.BatchCount, batchReader.Length);
+                    }
+
+                    for (var messageIdx = 0; messageIdx < batchHeader.BatchCount; ++messageIdx)
                     {
 
                         var messageHeader = new MessageHeader();
@@ -237,7 +269,7 @@ namespace Unity.Netcode
                         }
                         catch (OverflowException)
                         {
-                            NetworkLog.LogWarning("Received a batch that didn't have enough data for all of its batches, ending early!");
+                            NetworkLog.LogError("Received a batch that didn't have enough data for all of its batches, ending early!");
                             throw;
                         }
 
@@ -245,7 +277,7 @@ namespace Unity.Netcode
 
                         if (!batchReader.TryBeginRead((int)messageHeader.MessageSize))
                         {
-                            NetworkLog.LogWarning("Received a message that claimed a size larger than the packet, ending early!");
+                            NetworkLog.LogError("Received a message that claimed a size larger than the packet, ending early!");
                             return;
                         }
                         m_IncomingMessageQueue.Add(new ReceiveQueueItem
@@ -263,7 +295,7 @@ namespace Unity.Netcode
                     }
                     for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
                     {
-                        m_Hooks[hookIdx].OnAfterReceiveBatch(clientId, batchHeader.BatchSize, batchReader.Length);
+                        m_Hooks[hookIdx].OnAfterReceiveBatch(clientId, batchHeader.BatchCount, batchReader.Length);
                     }
                 }
             }
@@ -650,7 +682,7 @@ namespace Unity.Netcode
 
                 writeQueueItem.Writer.WriteBytes(headerSerializer.GetUnsafePtr(), headerSerializer.Length);
                 writeQueueItem.Writer.WriteBytes(tmpSerializer.GetUnsafePtr(), tmpSerializer.Length);
-                writeQueueItem.BatchHeader.BatchSize++;
+                writeQueueItem.BatchHeader.BatchCount++;
                 for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
                 {
                     m_Hooks[hookIdx].OnAfterSendMessage(clientId, ref message, delivery, tmpSerializer.Length + headerSerializer.Length);
@@ -745,7 +777,7 @@ namespace Unity.Netcode
                 for (var i = 0; i < sendQueueItem.Length; ++i)
                 {
                     ref var queueItem = ref sendQueueItem.ElementAt(i);
-                    if (queueItem.BatchHeader.BatchSize == 0)
+                    if (queueItem.BatchHeader.BatchCount == 0)
                     {
                         queueItem.Writer.Dispose();
                         continue;
@@ -753,23 +785,28 @@ namespace Unity.Netcode
 
                     for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
                     {
-                        m_Hooks[hookIdx].OnBeforeSendBatch(clientId, queueItem.BatchHeader.BatchSize, queueItem.Writer.Length, queueItem.NetworkDelivery);
+                        m_Hooks[hookIdx].OnBeforeSendBatch(clientId, queueItem.BatchHeader.BatchCount, queueItem.Writer.Length, queueItem.NetworkDelivery);
                     }
 
                     queueItem.Writer.Seek(0);
 #if UNITY_EDITOR || DEVELOPMENT_BUILD
                     // Skipping the Verify and sneaking the write mark in because we know it's fine.
-                    queueItem.Writer.Handle->AllowedWriteMark = 2;
+                    queueItem.Writer.Handle->AllowedWriteMark = sizeof(BatchHeader);
 #endif
+                    queueItem.BatchHeader.BatchHash = XXHash.Hash64(queueItem.Writer.GetUnsafePtr() + sizeof(BatchHeader), queueItem.Writer.Length - sizeof(BatchHeader));
+
+                    queueItem.BatchHeader.BatchSize = queueItem.Writer.Length;
+
                     queueItem.Writer.WriteValue(queueItem.BatchHeader);
 
+
                     try
                     {
                         m_MessageSender.Send(clientId, queueItem.NetworkDelivery, queueItem.Writer);
 
                         for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
                         {
-                            m_Hooks[hookIdx].OnAfterSendBatch(clientId, queueItem.BatchHeader.BatchSize, queueItem.Writer.Length, queueItem.NetworkDelivery);
+                            m_Hooks[hookIdx].OnAfterSendBatch(clientId, queueItem.BatchHeader.BatchCount, queueItem.Writer.Length, queueItem.NetworkDelivery);
                         }
                     }
                     finally

Runtime/NetworkVariable/NetworkVariableBase.cs

@@ -18,6 +18,11 @@ namespace Unity.Netcode
         /// </summary>
         private protected NetworkBehaviour m_NetworkBehaviour;
 
+        public NetworkBehaviour GetBehaviour()
+        {
+            return m_NetworkBehaviour;
+        }
+
         /// <summary>
         /// Initializes the NetworkVariable
         /// </summary>

Runtime/SceneManagement/NetworkSceneManager.cs

@@ -862,16 +862,6 @@ namespace Unity.Netcode
 
             SceneEventProgressTracking.Add(sceneEventProgress.Guid, sceneEventProgress);
 
-            if (!isUnloading)
-            {
-                // The Condition: While a scene is asynchronously loaded in single loading scene mode, if any new NetworkObjects are spawned
-                // they need to be moved into the do not destroy temporary scene
-                // When it is set: Just before starting the asynchronous loading call
-                // When it is unset: After the scene has loaded, the PopulateScenePlacedObjects is called, and all NetworkObjects in the do
-                // not destroy temporary scene are moved into the active scene
-                IsSpawnedObjectsPendingInDontDestroyOnLoad = true;
-            }
-
             m_IsSceneEventActive = true;
 
             // Set our callback delegate handler for completion
@@ -1162,6 +1152,13 @@ namespace Unity.Netcode
 
             if (sceneEventData.LoadSceneMode == LoadSceneMode.Single)
             {
+                // The Condition: While a scene is asynchronously loaded in single loading scene mode, if any new NetworkObjects are spawned
+                // they need to be moved into the do not destroy temporary scene
+                // When it is set: Just before starting the asynchronous loading call
+                // When it is unset: After the scene has loaded, the PopulateScenePlacedObjects is called, and all NetworkObjects in the do
+                // not destroy temporary scene are moved into the active scene
+                IsSpawnedObjectsPendingInDontDestroyOnLoad = true;
+
                 // Destroy current scene objects before switching.
                 m_NetworkManager.SpawnManager.ServerDestroySpawnedSceneObjects();
 

Runtime/Serialization/BufferSerializer.cs

@@ -7,14 +7,10 @@ namespace Unity.Netcode
     /// <summary>
     /// Two-way serializer wrapping FastBufferReader or FastBufferWriter.
     ///
-    /// Implemented as a ref struct for two reasons:
-    /// 1. The BufferSerializer cannot outlive the FBR/FBW it wraps or using it will cause a crash
-    /// 2. The BufferSerializer must always be passed by reference and can't be copied
+    /// Implemented as a ref struct to help enforce the requirement that
+    /// the BufferSerializer cannot outlive the FBR/FBW it wraps or using it will cause a crash
     ///
-    /// Ref structs help enforce both of those rules: they can't ref live the stack context in which they were
-    /// created, and they're always passed by reference no matter what.
-    ///
-    /// BufferSerializer doesn't wrapp FastBufferReader or FastBufferWriter directly because it can't.
+    /// BufferSerializer doesn't wrap FastBufferReader or FastBufferWriter directly because it can't.
     /// ref structs can't implement interfaces, and in order to be able to have two different implementations with
     /// the same interface (which allows us to avoid an "if(IsReader)" on every call), the thing directly wrapping
     /// the struct has to implement an interface. So IReaderWriter exists as the interface,

Runtime/Spawning/NetworkSpawnManager.cs

@@ -300,7 +300,7 @@ namespace Unity.Netcode
                 {
                     return true;
                 }
-                if (NetworkManager.NetworkConfig.NetworkPrefabOverrideLinks.TryGetValue(sceneObject.Hash, out var networkPrefab))
+                if (NetworkManager.NetworkConfig.Prefabs.NetworkPrefabOverrideLinks.TryGetValue(sceneObject.Hash, out var networkPrefab))
                 {
                     switch (networkPrefab.Override)
                     {
@@ -352,17 +352,17 @@ namespace Unity.Netcode
                 {
                     // See if there is a valid registered NetworkPrefabOverrideLink associated with the provided prefabHash
                     GameObject networkPrefabReference = null;
-                    if (NetworkManager.NetworkConfig.NetworkPrefabOverrideLinks.ContainsKey(globalObjectIdHash))
+                    if (NetworkManager.NetworkConfig.Prefabs.NetworkPrefabOverrideLinks.ContainsKey(globalObjectIdHash))
                     {
-                        switch (NetworkManager.NetworkConfig.NetworkPrefabOverrideLinks[globalObjectIdHash].Override)
+                        switch (NetworkManager.NetworkConfig.Prefabs.NetworkPrefabOverrideLinks[globalObjectIdHash].Override)
                         {
                             default:
                             case NetworkPrefabOverride.None:
-                                networkPrefabReference = NetworkManager.NetworkConfig.NetworkPrefabOverrideLinks[globalObjectIdHash].Prefab;
+                                networkPrefabReference = NetworkManager.NetworkConfig.Prefabs.NetworkPrefabOverrideLinks[globalObjectIdHash].Prefab;
                                 break;
                             case NetworkPrefabOverride.Hash:
                             case NetworkPrefabOverride.Prefab:
-                                networkPrefabReference = NetworkManager.NetworkConfig.NetworkPrefabOverrideLinks[globalObjectIdHash].OverridingTargetPrefab;
+                                networkPrefabReference = NetworkManager.NetworkConfig.Prefabs.NetworkPrefabOverrideLinks[globalObjectIdHash].OverridingTargetPrefab;
                                 break;
                         }
                     }
@@ -603,6 +603,11 @@ namespace Unity.Netcode
             var children = networkObject.GetComponentsInChildren<NetworkObject>();
             foreach (var childObject in children)
             {
+                // Do not propagate the in-scene object setting if a child was dynamically spawned.
+                if (childObject.IsSceneObject.HasValue && !childObject.IsSceneObject.Value)
+                {
+                    continue;
+                }
                 childObject.IsSceneObject = sceneObject;
             }
         }

Runtime/Transports/UTP/BatchedSendQueue.cs

@@ -226,7 +226,7 @@ namespace Unity.Netcode.Transports.UTP
                     {
                         writer.WriteInt(messageLength);
 
-                        var messageOffset = HeadIndex + reader.GetBytesRead();
+                        var messageOffset = reader.GetBytesRead();
                         WriteBytes(ref writer, (byte*)m_Data.GetUnsafePtr() + messageOffset, messageLength);
 
                         writerAvailable -= sizeof(int) + messageLength;

Runtime/Transports/UTP/UnityTransport.cs

@@ -145,7 +145,7 @@ namespace Unity.Netcode.Transports.UTP
 
         // Maximum reliable throughput, assuming the full reliable window can be sent on every
         // frame at 60 FPS. This will be a large over-estimation in any realistic scenario.
-        private const int k_MaxReliableThroughput = (NetworkParameterConstants.MTU * 32 * 60) / 1000; // bytes per millisecond
+        private const int k_MaxReliableThroughput = (NetworkParameterConstants.MTU * 64 * 60) / 1000; // bytes per millisecond
 
         private static ConnectionAddressData s_DefaultConnectionAddressData = new ConnectionAddressData { Address = "127.0.0.1", Port = 7777, ServerListenAddress = string.Empty };
 
@@ -303,20 +303,23 @@ namespace Unity.Netcode.Transports.UTP
             public ushort Port;
 
             /// <summary>
-            /// IP address the server will listen on. If not provided, will use 'Address'.
+            /// IP address the server will listen on. If not provided, will use localhost.
             /// </summary>
-            [Tooltip("IP address the server will listen on. If not provided, will use 'Address'.")]
+            [Tooltip("IP address the server will listen on. If not provided, will use localhost.")]
             [SerializeField]
             public string ServerListenAddress;
 
-            private static NetworkEndpoint ParseNetworkEndpoint(string ip, ushort port)
+            private static NetworkEndpoint ParseNetworkEndpoint(string ip, ushort port, bool silent = false)
             {
                 NetworkEndpoint endpoint = default;
 
                 if (!NetworkEndpoint.TryParse(ip, port, out endpoint, NetworkFamily.Ipv4) &&
                     !NetworkEndpoint.TryParse(ip, port, out endpoint, NetworkFamily.Ipv6))
                 {
-                    Debug.LogError($"Invalid network endpoint: {ip}:{port}.");
+                    if (!silent)
+                    {
+                        Debug.LogError($"Invalid network endpoint: {ip}:{port}.");
+                    }
                 }
 
                 return endpoint;
@@ -330,9 +333,34 @@ namespace Unity.Netcode.Transports.UTP
             /// <summary>
             /// Endpoint (IP address and port) server will listen/bind on.
             /// </summary>
-            public NetworkEndpoint ListenEndPoint => ParseNetworkEndpoint((ServerListenAddress?.Length == 0) ? Address : ServerListenAddress, Port);
+            public NetworkEndpoint ListenEndPoint
+            {
+                get
+                {
+                    if (string.IsNullOrEmpty(ServerListenAddress))
+                    {
+                        var ep = NetworkEndpoint.LoopbackIpv4;
+
+                        // If an address was entered and it's IPv6, switch to using ::1 as the
+                        // default listen address. (Otherwise we always assume IPv4.)
+                        if (!string.IsNullOrEmpty(Address) && ServerEndPoint.Family == NetworkFamily.Ipv6)
+                        {
+                            ep = NetworkEndpoint.LoopbackIpv6;
+                        }
+
+                        return ep.WithPort(Port);
+                    }
+                    else
+                    {
+                        return ParseNetworkEndpoint(ServerListenAddress, Port);
+                    }
+                }
+            }
+
+            public bool IsIpv6 => !string.IsNullOrEmpty(Address) && ParseNetworkEndpoint(Address, Port, true).Family == NetworkFamily.Ipv6;
         }
 
+
         /// <summary>
         /// The connection (address) data for this <see cref="UnityTransport"/> instance.
         /// This is where you can change IP Address, Port, or server's listen address.
@@ -529,14 +557,14 @@ namespace Unity.Netcode.Transports.UTP
             int result = m_Driver.Bind(endPoint);
             if (result != 0)
             {
-                Debug.LogError("Server failed to bind");
+                Debug.LogError("Server failed to bind. This is usually caused by another process being bound to the same port.");
                 return false;
             }
 
             result = m_Driver.Listen();
             if (result != 0)
             {
-                Debug.LogError("Server failed to listen");
+                Debug.LogError("Server failed to listen.");
                 return false;
             }
 
@@ -609,7 +637,7 @@ namespace Unity.Netcode.Transports.UTP
             {
                 Address = ipv4Address,
                 Port = port,
-                ServerListenAddress = listenAddress ?? string.Empty
+                ServerListenAddress = listenAddress ?? ipv4Address
             };
 
             SetProtocol(ProtocolType.UnityTransport);
@@ -1153,17 +1181,20 @@ namespace Unity.Netcode.Transports.UTP
 
             m_NetworkSettings = new NetworkSettings(Allocator.Persistent);
 
-#if !UNITY_WEBGL
             // If the user sends a message of exactly m_MaxPayloadSize in length, we need to
             // account for the overhead of its length when we store it in the send queue.
             var fragmentationCapacity = m_MaxPayloadSize + BatchedSendQueue.PerMessageOverhead;
-
             m_NetworkSettings.WithFragmentationStageParameters(payloadCapacity: fragmentationCapacity);
-#if !UTP_TRANSPORT_2_0_ABOVE
+
+            // Bump the reliable window size to its maximum size of 64. Since NGO makes heavy use of
+            // reliable delivery, we're better off with the increased window size compared to the
+            // extra 4 bytes of header that this costs us.
+            m_NetworkSettings.WithReliableStageParameters(windowSize: 64);
+
+#if !UTP_TRANSPORT_2_0_ABOVE && !UNITY_WEBGL
             m_NetworkSettings.WithBaselibNetworkInterfaceParameters(
                 receiveQueueCapacity: m_MaxPacketQueueSize,
                 sendQueueCapacity: m_MaxPacketQueueSize);
-#endif
 #endif
         }
 
@@ -1449,7 +1480,7 @@ namespace Unity.Netcode.Transports.UTP
                 heartbeatTimeoutMS: transport.m_HeartbeatTimeoutMS);
 
 #if UNITY_WEBGL && !UNITY_EDITOR
-            if (NetworkManager.IsServer)
+            if (NetworkManager.IsServer && m_ProtocolType != ProtocolType.RelayUnityTransport)
             {
                 throw new Exception("WebGL as a server is not supported by Unity Transport, outside the Editor.");
             }
@@ -1473,7 +1504,7 @@ namespace Unity.Netcode.Transports.UTP
                 {
                     if (NetworkManager.IsServer)
                     {
-                        if (String.IsNullOrEmpty(m_ServerCertificate) || String.IsNullOrEmpty(m_ServerPrivateKey))
+                        if (string.IsNullOrEmpty(m_ServerCertificate) || string.IsNullOrEmpty(m_ServerPrivateKey))
                         {
                             throw new Exception("In order to use encrypted communications, when hosting, you must set the server certificate and key.");
                         }
@@ -1482,11 +1513,11 @@ namespace Unity.Netcode.Transports.UTP
                     }
                     else
                     {
-                        if (String.IsNullOrEmpty(m_ServerCommonName))
+                        if (string.IsNullOrEmpty(m_ServerCommonName))
                         {
                             throw new Exception("In order to use encrypted communications, clients must set the server common name.");
                         }
-                        else if (String.IsNullOrEmpty(m_ClientCaCertificate))
+                        else if (string.IsNullOrEmpty(m_ClientCaCertificate))
                         {
                             m_NetworkSettings.WithSecureClientParameters(m_ServerCommonName);
                         }

TestHelpers/Runtime/AssemblyInfo.cs

@@ -1,6 +1,12 @@
 using System.Runtime.CompilerServices;
 
-[assembly: InternalsVisibleTo("TestProject.EditorTests")]
-[assembly: InternalsVisibleTo("TestProject.RuntimeTests")]
-[assembly: InternalsVisibleTo("TestProject.ToolsIntegration.RuntimeTests")]
+#if UNITY_INCLUDE_TESTS
 [assembly: InternalsVisibleTo("Unity.Netcode.RuntimeTests")]
+[assembly: InternalsVisibleTo("TestProject.RuntimeTests")]
+#if UNITY_EDITOR
+[assembly: InternalsVisibleTo("TestProject.EditorTests")]
+#endif // UNITY_EDITOR
+#if MULTIPLAYER_TOOLS
+[assembly: InternalsVisibleTo("TestProject.ToolsIntegration.RuntimeTests")]
+#endif // MULTIPLAYER_TOOLS
+#endif // UNITY_INCLUDE_TESTS

TestHelpers/Runtime/NetcodeIntegrationTest.cs

@@ -241,11 +241,20 @@ namespace Unity.Netcode.TestHelpers.Runtime
         {
         }
 
+        /// <summary>
+        /// Invoked immediately after the player prefab GameObject is created
+        /// prior to adding a NetworkObject component
+        /// </summary>
+        protected virtual void OnPlayerPrefabGameObjectCreated()
+        {
+        }
+
         private void CreatePlayerPrefab()
         {
             VerboseDebug($"Entering {nameof(CreatePlayerPrefab)}");
             // Create playerPrefab
             m_PlayerPrefab = new GameObject("Player");
+            OnPlayerPrefabGameObjectCreated();
             NetworkObject networkObject = m_PlayerPrefab.AddComponent<NetworkObject>();
 
             // Make it a prefab
@@ -692,6 +701,7 @@ namespace Unity.Netcode.TestHelpers.Runtime
             }
 
             VerboseDebug($"Exiting {nameof(TearDown)}");
+            LogWaitForMessages();
             NetcodeLogAssert.Dispose();
         }
 
@@ -920,18 +930,7 @@ namespace Unity.Netcode.TestHelpers.Runtime
             Assert.IsNotNull(m_ServerNetworkManager, prefabCreateAssertError);
             Assert.IsFalse(m_ServerNetworkManager.IsListening, prefabCreateAssertError);
 
-            var gameObject = new GameObject();
-            gameObject.name = baseName;
-            var networkObject = gameObject.AddComponent<NetworkObject>();
-            networkObject.NetworkManagerOwner = m_ServerNetworkManager;
-            NetcodeIntegrationTestHelpers.MakeNetworkObjectTestPrefab(networkObject);
-            var networkPrefab = new NetworkPrefab() { Prefab = gameObject };
-            m_ServerNetworkManager.NetworkConfig.NetworkPrefabs.Add(networkPrefab);
-            foreach (var clientNetworkManager in m_ClientNetworkManagers)
-            {
-                clientNetworkManager.NetworkConfig.NetworkPrefabs.Add(networkPrefab);
-            }
-            return gameObject;
+            return NetcodeIntegrationTestHelpers.CreateNetworkObjectPrefab(baseName, m_ServerNetworkManager, m_ClientNetworkManagers);
         }
 
         /// <summary>
@@ -1059,5 +1058,61 @@ namespace Unity.Netcode.TestHelpers.Runtime
                 var asyncOperation = SceneManager.UnloadSceneAsync(scene);
             }
         }
+
+        private System.Text.StringBuilder m_WaitForLog = new System.Text.StringBuilder();
+
+        private void LogWaitForMessages()
+        {
+            VerboseDebug(m_WaitForLog.ToString());
+            m_WaitForLog.Clear();
+        }
+
+        private IEnumerator WaitForTickAndFrames(NetworkManager networkManager, int tickCount, float targetFrames)
+        {
+            var tickAndFramesConditionMet = false;
+            var frameCount = 0;
+            var waitForFixedUpdate = new WaitForFixedUpdate();
+            m_WaitForLog.Append($"[NetworkManager-{networkManager.LocalClientId}][WaitForTicks-Begin] Waiting for ({tickCount}) network ticks and ({targetFrames}) frames to pass.\n");
+            var tickStart = networkManager.NetworkTickSystem.LocalTime.Tick;
+            while (!tickAndFramesConditionMet)
+            {
+                // Wait until both tick and frame counts have reached their targeted values
+                if ((networkManager.NetworkTickSystem.LocalTime.Tick - tickStart) >= tickCount && frameCount >= targetFrames)
+                {
+                    tickAndFramesConditionMet = true;
+                }
+                else
+                {
+                    yield return waitForFixedUpdate;
+                    frameCount++;
+                    // In the event something is broken with time systems (or the like)
+                    // Exit if we have exceeded 1000 frames
+                    if (frameCount >= 1000.0f)
+                    {
+                        tickAndFramesConditionMet = true;
+                    }
+                }
+            }
+            m_WaitForLog.Append($"[NetworkManager-{networkManager.LocalClientId}][WaitForTicks-End] Waited for ({networkManager.NetworkTickSystem.LocalTime.Tick - tickStart}) network ticks and ({frameCount}) frames to pass.\n");
+            yield break;
+        }
+
+        /// <summary>
+        /// Yields until specified amount of network ticks and the expected number of frames has been passed.
+        /// </summary>
+        protected IEnumerator WaitForTicks(NetworkManager networkManager, int count)
+        {
+            var targetTick = networkManager.NetworkTickSystem.LocalTime.Tick + count;
+
+            // Calculate the expected number of frame updates that should occur during the tick count wait period
+            var frameFrequency = 1.0f / (Application.targetFrameRate >= 60 && Application.targetFrameRate <= 100 ? Application.targetFrameRate : 60.0f);
+            var tickFrequency = 1.0f / networkManager.NetworkConfig.TickRate;
+            var framesPerTick = tickFrequency / frameFrequency;
+
+            // Total number of frames to occur over the specified number of ticks
+            var totalFrameCount = framesPerTick * count;
+            m_WaitForLog.Append($"[NetworkManager-{networkManager.LocalClientId}][WaitForTicks] TickRate ({networkManager.NetworkConfig.TickRate}) | Tick Wait ({count}) | TargetFrameRate ({Application.targetFrameRate}) | Target Frames ({framesPerTick * count})\n");
+            yield return WaitForTickAndFrames(networkManager, count, totalFrameCount);
+        }
     }
 }

TestHelpers/Runtime/NetcodeIntegrationTestHelpers.cs

@@ -182,11 +182,8 @@ namespace Unity.Netcode.TestHelpers.Runtime
             unityTransport.ConnectTimeoutMS = 500;
 
             // Set the NetworkConfig
-            networkManager.NetworkConfig = new NetworkConfig()
-            {
-                // Set transport
-                NetworkTransport = unityTransport
-            };
+            networkManager.NetworkConfig ??= new NetworkConfig();
+            networkManager.NetworkConfig.NetworkTransport = unityTransport;
         }
 
         public static NetworkManager CreateServer()
@@ -486,6 +483,34 @@ namespace Unity.Netcode.TestHelpers.Runtime
             }
         }
 
+        public static GameObject CreateNetworkObjectPrefab(string baseName, NetworkManager server, params NetworkManager[] clients)
+        {
+            void AddNetworkPrefab(NetworkConfig config, NetworkPrefab prefab)
+            {
+                config.Prefabs.Add(prefab);
+            }
+
+            var prefabCreateAssertError = $"You can only invoke this method before starting the network manager(s)!";
+            Assert.IsNotNull(server, prefabCreateAssertError);
+            Assert.IsFalse(server.IsListening, prefabCreateAssertError);
+
+            var gameObject = new GameObject();
+            gameObject.name = baseName;
+            var networkObject = gameObject.AddComponent<NetworkObject>();
+            networkObject.NetworkManagerOwner = server;
+            MakeNetworkObjectTestPrefab(networkObject);
+            var networkPrefab = new NetworkPrefab() { Prefab = gameObject };
+
+            // We could refactor this test framework to share a NetworkPrefabList instance, but at this point it's
+            // probably more trouble than it's worth to verify these lists stay in sync across all tests...
+            AddNetworkPrefab(server.NetworkConfig, networkPrefab);
+            foreach (var clientNetworkManager in clients)
+            {
+                AddNetworkPrefab(clientNetworkManager.NetworkConfig, networkPrefab);
+            }
+            return gameObject;
+        }
+
         // We use GameObject instead of SceneObject to be able to keep hierarchy
         public static void MarkAsSceneObjectRoot(GameObject networkObjectRoot, NetworkManager server, NetworkManager[] clients)
         {
@@ -512,15 +537,6 @@ namespace Unity.Netcode.TestHelpers.Runtime
             }
         }
 
-        /// <summary>
-        /// Waits (yields) until specified amount of network ticks has been passed.
-        /// </summary>
-        public static IEnumerator WaitForTicks(NetworkManager networkManager, int count)
-        {
-            var targetTick = networkManager.NetworkTickSystem.LocalTime.Tick + count;
-            yield return new WaitUntil(() => networkManager.NetworkTickSystem.LocalTime.Tick >= targetTick);
-        }
-
         /// <summary>
         /// Waits on the client side to be connected.
         /// </summary>

Tests/Editor/Build/BuildTests.cs

@@ -12,7 +12,6 @@ namespace Unity.Netcode.EditorTests
         public const string DefaultBuildScenePath = "Tests/Editor/Build/BuildTestScene.unity";
 
         [Test]
-        [Ignore("Disabling this test on release/1.2.0 branch due to Burst failures caused when running with upm ci")]
         public void BasicBuildTest()
         {
             var execAssembly = Assembly.GetExecutingAssembly();

Tests/Editor/Messaging/MessageCorruptionTests.cs

@@ -0,0 +1,203 @@
+using System;
+using System.Collections.Generic;
+using System.Text.RegularExpressions;
+using NUnit.Framework;
+using NUnit.Framework.Internal;
+using Unity.Collections;
+using Unity.Collections.LowLevel.Unsafe;
+using UnityEngine;
+using UnityEngine.TestTools;
+
+namespace Unity.Netcode.EditorTests
+{
+    public class MessageCorruptionTests
+    {
+
+        private struct TestMessage : INetworkMessage, INetworkSerializeByMemcpy
+        {
+            public ForceNetworkSerializeByMemcpy<Guid> Value;
+            public static bool Handled;
+            public static bool Deserialized;
+
+            public void Serialize(FastBufferWriter writer, int targetVersion)
+            {
+                writer.WriteValueSafe(Value);
+            }
+
+            public bool Deserialize(FastBufferReader reader, ref NetworkContext context, int receivedMessageVersion)
+            {
+                Deserialized = true;
+                reader.ReadValueSafe(out Value);
+                return true;
+            }
+
+            public void Handle(ref NetworkContext context)
+            {
+                Handled = true;
+            }
+
+            public int Version => 0;
+        }
+
+        private class TestMessageProvider : IMessageProvider
+        {
+            public List<MessagingSystem.MessageWithHandler> GetMessages()
+            {
+                return new List<MessagingSystem.MessageWithHandler>
+                {
+                    new MessagingSystem.MessageWithHandler
+                    {
+                        MessageType = typeof(TestMessage),
+                        Handler = MessagingSystem.ReceiveMessage<TestMessage>,
+                        GetVersion = MessagingSystem.CreateMessageAndGetVersion<TestMessage>
+                    }
+                };
+            }
+        }
+
+        public enum TypeOfCorruption
+        {
+            OffsetPlus,
+            OffsetMinus,
+            CorruptBytes,
+            Truncated,
+            AdditionalGarbageData,
+        }
+
+        private class TestMessageSender : IMessageSender
+        {
+
+            public TypeOfCorruption Corruption;
+            public List<byte[]> MessageQueue = new List<byte[]>();
+
+            public unsafe void Send(ulong clientId, NetworkDelivery delivery, FastBufferWriter batchData)
+            {
+                switch (Corruption)
+                {
+                    case TypeOfCorruption.OffsetPlus:
+                        {
+                            using var subWriter = new FastBufferWriter(batchData.Length + 1, Allocator.Temp);
+                            subWriter.WriteByteSafe(0);
+                            subWriter.WriteBytesSafe(batchData.GetUnsafePtr(), batchData.Length);
+                            MessageQueue.Add(subWriter.ToArray());
+                            break;
+                        }
+                    case TypeOfCorruption.OffsetMinus:
+                        {
+                            using var subWriter = new FastBufferWriter(batchData.Length - 1, Allocator.Temp);
+                            subWriter.WriteBytesSafe(batchData.GetUnsafePtr() + 1, batchData.Length - 1);
+                            MessageQueue.Add(subWriter.ToArray());
+                            break;
+                        }
+                    case TypeOfCorruption.CorruptBytes:
+                        batchData.Seek(batchData.Length - 2);
+                        var currentByte = batchData.GetUnsafePtr()[0];
+                        batchData.WriteByteSafe((byte)(currentByte == 0 ? 1 : 0));
+                        MessageQueue.Add(batchData.ToArray());
+                        break;
+                    case TypeOfCorruption.Truncated:
+                        batchData.Truncate(batchData.Length - 1);
+                        MessageQueue.Add(batchData.ToArray());
+                        break;
+                    case TypeOfCorruption.AdditionalGarbageData:
+                        batchData.Seek(batchData.Length);
+                        batchData.WriteByteSafe(0);
+                        MessageQueue.Add(batchData.ToArray());
+                        break;
+                }
+            }
+        }
+
+        private MessagingSystem m_MessagingSystem;
+        private TestMessageSender m_MessageSender;
+
+        [SetUp]
+        public void SetUp()
+        {
+            TestMessage.Handled = false;
+            TestMessage.Deserialized = false;
+            m_MessageSender = new TestMessageSender();
+
+            m_MessagingSystem = new MessagingSystem(m_MessageSender, this, new TestMessageProvider());
+
+            m_MessagingSystem.ClientConnected(0);
+            m_MessagingSystem.SetVersion(0, XXHash.Hash32(typeof(TestMessage).FullName), 0);
+        }
+
+        [TearDown]
+        public void TearDown()
+        {
+            m_MessagingSystem.Dispose();
+        }
+
+        private TestMessage GetMessage()
+        {
+            return new TestMessage
+            {
+                Value = Guid.NewGuid()
+            };
+        }
+
+        [Test]
+        public unsafe void WhenPacketsAreCorrupted_TheyDontGetProcessed([Values] TypeOfCorruption typeOfCorruption)
+        {
+            m_MessageSender.Corruption = typeOfCorruption;
+
+            switch (typeOfCorruption)
+            {
+                case TypeOfCorruption.OffsetMinus:
+                case TypeOfCorruption.OffsetPlus:
+                    LogAssert.Expect(LogType.Error, new Regex("Received a packet with an invalid Magic Value\\."));
+                    break;
+                case TypeOfCorruption.Truncated:
+                case TypeOfCorruption.AdditionalGarbageData:
+                    LogAssert.Expect(LogType.Error, new Regex("Received a packet with an invalid Batch Size Value\\."));
+                    break;
+                case TypeOfCorruption.CorruptBytes:
+                    LogAssert.Expect(LogType.Error, new Regex("Received a packet with an invalid Hash Value\\."));
+                    break;
+            }
+
+            // Dummy batch header
+            var batchHeader = new BatchHeader
+            {
+                BatchCount = 1
+            };
+            var messageHeader = new MessageHeader
+            {
+                MessageSize = (ushort)UnsafeUtility.SizeOf<TestMessage>(),
+                MessageType = m_MessagingSystem.GetMessageType(typeof(TestMessage)),
+            };
+            var message = GetMessage();
+
+            var writer = new FastBufferWriter(1300, Allocator.Temp);
+            using (writer)
+            {
+                writer.TryBeginWrite(FastBufferWriter.GetWriteSize(batchHeader) +
+                                     FastBufferWriter.GetWriteSize(messageHeader) +
+                                     FastBufferWriter.GetWriteSize(message));
+                writer.WriteValue(batchHeader);
+                writer.WriteValue(messageHeader);
+                writer.WriteValue(message);
+
+                // Fill out the rest of the batch header
+                writer.Seek(0);
+                batchHeader = new BatchHeader
+                {
+                    Magic = BatchHeader.MagicValue,
+                    BatchSize = writer.Length,
+                    BatchHash = XXHash.Hash64(writer.GetUnsafePtr() + sizeof(BatchHeader), writer.Length - sizeof(BatchHeader)),
+                    BatchCount = 1
+                };
+                writer.WriteValue(batchHeader);
+                m_MessageSender.Send(0, NetworkDelivery.Reliable, writer);
+
+                var receivedMessage = m_MessageSender.MessageQueue[0];
+                m_MessageSender.MessageQueue.Clear();
+                m_MessagingSystem.HandleIncomingData(0, new ArraySegment<byte>(receivedMessage), 0);
+                Assert.IsFalse(TestMessage.Deserialized);
+                Assert.IsFalse(TestMessage.Handled);
+            }
+        }
+    }
+}

Tests/Editor/Messaging/MessageCorruptionTests.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: d3c01a0b5a0e478ebc5182fe339bde04
+timeCreated: 1676997550

Tests/Editor/Messaging/MessageReceivingTests.cs

@@ -114,11 +114,11 @@ namespace Unity.Netcode.EditorTests
         }
 
         [Test]
-        public void WhenHandlingIncomingData_ReceiveIsNotCalledBeforeProcessingIncomingMessageQueue()
+        public unsafe void WhenHandlingIncomingData_ReceiveIsNotCalledBeforeProcessingIncomingMessageQueue()
         {
             var batchHeader = new BatchHeader
             {
-                BatchSize = 1
+                BatchCount = 1
             };
             var messageHeader = new MessageHeader
             {
@@ -137,6 +137,17 @@ namespace Unity.Netcode.EditorTests
                 writer.WriteValue(messageHeader);
                 writer.WriteValue(message);
 
+                // Fill out the rest of the batch header
+                writer.Seek(0);
+                batchHeader = new BatchHeader
+                {
+                    Magic = BatchHeader.MagicValue,
+                    BatchSize = writer.Length,
+                    BatchHash = XXHash.Hash64(writer.GetUnsafePtr() + sizeof(BatchHeader), writer.Length - sizeof(BatchHeader)),
+                    BatchCount = 1
+                };
+                writer.WriteValue(batchHeader);
+
                 var reader = new FastBufferReader(writer, Allocator.Temp);
                 using (reader)
                 {
@@ -149,11 +160,11 @@ namespace Unity.Netcode.EditorTests
         }
 
         [Test]
-        public void WhenReceivingAMessageAndProcessingMessageQueue_ReceiveMethodIsCalled()
+        public unsafe void WhenReceivingAMessageAndProcessingMessageQueue_ReceiveMethodIsCalled()
         {
             var batchHeader = new BatchHeader
             {
-                BatchSize = 1
+                BatchCount = 1
             };
             var messageHeader = new MessageHeader
             {
@@ -170,6 +181,17 @@ namespace Unity.Netcode.EditorTests
                 BytePacker.WriteValueBitPacked(writer, messageHeader.MessageSize);
                 writer.WriteValueSafe(message);
 
+                // Fill out the rest of the batch header
+                writer.Seek(0);
+                batchHeader = new BatchHeader
+                {
+                    Magic = BatchHeader.MagicValue,
+                    BatchSize = writer.Length,
+                    BatchHash = XXHash.Hash64(writer.GetUnsafePtr() + sizeof(BatchHeader), writer.Length - sizeof(BatchHeader)),
+                    BatchCount = 1
+                };
+                writer.WriteValue(batchHeader);
+
                 var reader = new FastBufferReader(writer, Allocator.Temp);
                 using (reader)
                 {
@@ -184,11 +206,11 @@ namespace Unity.Netcode.EditorTests
         }
 
         [Test]
-        public void WhenReceivingMultipleMessagesAndProcessingMessageQueue_ReceiveMethodIsCalledMultipleTimes()
+        public unsafe void WhenReceivingMultipleMessagesAndProcessingMessageQueue_ReceiveMethodIsCalledMultipleTimes()
         {
             var batchHeader = new BatchHeader
             {
-                BatchSize = 2
+                BatchCount = 2
             };
             var messageHeader = new MessageHeader
             {
@@ -209,6 +231,17 @@ namespace Unity.Netcode.EditorTests
                 BytePacker.WriteValueBitPacked(writer, messageHeader.MessageSize);
                 writer.WriteValueSafe(message2);
 
+                // Fill out the rest of the batch header
+                writer.Seek(0);
+                batchHeader = new BatchHeader
+                {
+                    Magic = BatchHeader.MagicValue,
+                    BatchSize = writer.Length,
+                    BatchHash = XXHash.Hash64(writer.GetUnsafePtr() + sizeof(BatchHeader), writer.Length - sizeof(BatchHeader)),
+                    BatchCount = 2
+                };
+                writer.WriteValue(batchHeader);
+
                 var reader = new FastBufferReader(writer, Allocator.Temp);
                 using (reader)
                 {

Tests/Editor/Messaging/MessageSendingTests.cs

@@ -155,7 +155,7 @@ namespace Unity.Netcode.EditorTests
         {
             var message = GetMessage();
             var size = UnsafeUtility.SizeOf<TestMessage>() + 2; // MessageHeader packed with this message will be 2 bytes
-            for (var i = 0; i < 1300 / size; ++i)
+            for (var i = 0; i < (1300 - UnsafeUtility.SizeOf<BatchHeader>()) / size; ++i)
             {
                 m_MessagingSystem.SendMessage(ref message, NetworkDelivery.Reliable, m_Clients);
             }
@@ -169,7 +169,7 @@ namespace Unity.Netcode.EditorTests
         {
             var message = GetMessage();
             var size = UnsafeUtility.SizeOf<TestMessage>() + 2; // MessageHeader packed with this message will be 2 bytes
-            for (var i = 0; i < (1300 / size) + 1; ++i)
+            for (var i = 0; i < ((1300 - UnsafeUtility.SizeOf<BatchHeader>()) / size) + 1; ++i)
             {
                 m_MessagingSystem.SendMessage(ref message, NetworkDelivery.Reliable, m_Clients);
             }
@@ -183,7 +183,7 @@ namespace Unity.Netcode.EditorTests
         {
             var message = GetMessage();
             var size = UnsafeUtility.SizeOf<TestMessage>() + 2; // MessageHeader packed with this message will be 2 bytes
-            for (var i = 0; i < (1300 / size) + 1; ++i)
+            for (var i = 0; i < ((1300 - UnsafeUtility.SizeOf<BatchHeader>()) / size) + 1; ++i)
             {
                 m_MessagingSystem.SendMessage(ref message, NetworkDelivery.ReliableFragmentedSequenced, m_Clients);
             }
@@ -229,7 +229,7 @@ namespace Unity.Netcode.EditorTests
             using (reader)
             {
                 reader.ReadValueSafe(out BatchHeader header);
-                Assert.AreEqual(2, header.BatchSize);
+                Assert.AreEqual(2, header.BatchCount);
 
                 MessageHeader messageHeader;
 

Tests/Editor/NetworkManagerConfigurationTests.cs

@@ -1,6 +1,8 @@
+using System.Collections.Generic;
 using NUnit.Framework;
 using UnityEngine;
 using Unity.Netcode.Editor;
+using Unity.Netcode.Transports.UTP;
 using UnityEditor.SceneManagement;
 using UnityEngine.SceneManagement;
 using UnityEngine.TestTools;
@@ -105,12 +107,188 @@ namespace Unity.Netcode.EditorTests
             networkManager.OnValidate();
 
             // Expect a warning
-            LogAssert.Expect(LogType.Warning, $"[Netcode] {NetworkManager.PrefabDebugHelper(networkManager.NetworkConfig.NetworkPrefabs[0])} has child {nameof(NetworkObject)}(s) but they will not be spawned across the network (unsupported {nameof(NetworkPrefab)} setup)");
+            LogAssert.Expect(LogType.Warning, $"[Netcode] {NetworkManager.PrefabDebugHelper(networkManager.NetworkConfig.Prefabs.Prefabs[0])} has child {nameof(NetworkObject)}(s) but they will not be spawned across the network (unsupported {nameof(NetworkPrefab)} setup)");
 
             // Clean up
             Object.DestroyImmediate(networkManagerObject);
             Object.DestroyImmediate(parent);
 
         }
+
+        [Test]
+        public void WhenNetworkConfigContainsOldPrefabList_TheyMigrateProperlyToTheNewList()
+        {
+            var networkConfig = new NetworkConfig();
+
+            var regularPrefab = new GameObject("Regular Prefab").AddComponent<NetworkObject>();
+            var overriddenPrefab = new GameObject("Overridden Prefab").AddComponent<NetworkObject>();
+            var overridingTargetPrefab = new GameObject("Overriding Target Prefab").AddComponent<NetworkObject>();
+            var sourcePrefabToOverride = new GameObject("Overriding Source Prefab").AddComponent<NetworkObject>();
+
+            regularPrefab.GlobalObjectIdHash = 1;
+            overriddenPrefab.GlobalObjectIdHash = 2;
+            overridingTargetPrefab.GlobalObjectIdHash = 3;
+            sourcePrefabToOverride.GlobalObjectIdHash = 4;
+
+            networkConfig.OldPrefabList = new List<NetworkPrefab>();
+            networkConfig.OldPrefabList.Add(new NetworkPrefab { Prefab = regularPrefab.gameObject });
+            networkConfig.OldPrefabList.Add(new NetworkPrefab { Prefab = overriddenPrefab.gameObject, Override = NetworkPrefabOverride.Prefab, OverridingTargetPrefab = overridingTargetPrefab.gameObject, SourcePrefabToOverride = sourcePrefabToOverride.gameObject, SourceHashToOverride = 123456 });
+
+            networkConfig.InitializePrefabs();
+
+            Assert.IsNull(networkConfig.OldPrefabList);
+            Assert.IsNotNull(networkConfig.Prefabs);
+            Assert.IsNotNull(networkConfig.Prefabs.Prefabs);
+            Assert.AreEqual(2, networkConfig.Prefabs.Prefabs.Count);
+
+            Assert.AreSame(regularPrefab.gameObject, networkConfig.Prefabs.Prefabs[0].Prefab);
+            Assert.AreEqual(NetworkPrefabOverride.None, networkConfig.Prefabs.Prefabs[0].Override);
+            Assert.IsNull(networkConfig.Prefabs.Prefabs[0].SourcePrefabToOverride);
+            Assert.IsNull(networkConfig.Prefabs.Prefabs[0].OverridingTargetPrefab);
+
+            Assert.AreSame(overriddenPrefab.gameObject, networkConfig.Prefabs.Prefabs[1].Prefab);
+            Assert.AreEqual(NetworkPrefabOverride.Prefab, networkConfig.Prefabs.Prefabs[1].Override);
+            Assert.AreEqual(123456, networkConfig.Prefabs.Prefabs[1].SourceHashToOverride);
+            Assert.AreSame(sourcePrefabToOverride.gameObject, networkConfig.Prefabs.Prefabs[1].SourcePrefabToOverride);
+            Assert.AreSame(overridingTargetPrefab.gameObject, networkConfig.Prefabs.Prefabs[1].OverridingTargetPrefab);
+        }
+
+        [Test]
+        public void WhenModifyingPrefabListUsingNetworkManagerAPI_ModificationIsLocal()
+        {
+            // Setup
+            var networkManagerObject = new GameObject(nameof(NestedNetworkObjectPrefabCheck));
+            var networkManager = networkManagerObject.AddComponent<NetworkManager>();
+            networkManager.NetworkConfig = new NetworkConfig();
+            networkManager.NetworkConfig.NetworkTransport = networkManager.gameObject.AddComponent<UnityTransport>();
+
+            var networkManagerObject2 = new GameObject(nameof(NestedNetworkObjectPrefabCheck));
+            var networkManager2 = networkManagerObject2.AddComponent<NetworkManager>();
+            networkManager2.NetworkConfig = new NetworkConfig();
+            networkManager2.NetworkConfig.NetworkTransport = networkManager.gameObject.AddComponent<UnityTransport>();
+
+            var object1 = new GameObject("Object 1").AddComponent<NetworkObject>();
+            var object2 = new GameObject("Object 2").AddComponent<NetworkObject>();
+            var object3 = new GameObject("Object 3").AddComponent<NetworkObject>();
+
+            object1.GlobalObjectIdHash = 1;
+            object2.GlobalObjectIdHash = 2;
+            object3.GlobalObjectIdHash = 3;
+
+            var sharedList = ScriptableObject.CreateInstance<NetworkPrefabsList>();
+            sharedList.List.Add(new NetworkPrefab { Prefab = object1.gameObject });
+
+            networkManager.NetworkConfig.Prefabs.NetworkPrefabsLists = new List<NetworkPrefabsList> { sharedList };
+            networkManager2.NetworkConfig.Prefabs.NetworkPrefabsLists = new List<NetworkPrefabsList> { sharedList };
+
+            networkManager.Initialize(true);
+            networkManager2.Initialize(false);
+
+            networkManager.AddNetworkPrefab(object2.gameObject);
+            networkManager2.AddNetworkPrefab(object3.gameObject);
+
+            Assert.IsTrue(networkManager.NetworkConfig.Prefabs.Contains(object1.gameObject));
+            Assert.IsTrue(networkManager2.NetworkConfig.Prefabs.Contains(object1.gameObject));
+            Assert.IsTrue(networkManager.NetworkConfig.Prefabs.Contains(object2.gameObject));
+            Assert.IsFalse(networkManager2.NetworkConfig.Prefabs.Contains(object2.gameObject));
+            Assert.IsTrue(networkManager2.NetworkConfig.Prefabs.Contains(object3.gameObject));
+            Assert.IsFalse(networkManager.NetworkConfig.Prefabs.Contains(object3.gameObject));
+
+            Assert.IsTrue(sharedList.Contains(object1.gameObject));
+            Assert.IsFalse(sharedList.Contains(object2.gameObject));
+            Assert.IsFalse(sharedList.Contains(object3.gameObject));
+        }
+
+        [Test]
+        public void WhenModifyingPrefabListUsingPrefabsAPI_ModificationIsLocal()
+        {
+            // Setup
+            var networkManagerObject = new GameObject(nameof(NestedNetworkObjectPrefabCheck));
+            var networkManager = networkManagerObject.AddComponent<NetworkManager>();
+            networkManager.NetworkConfig = new NetworkConfig();
+            networkManager.NetworkConfig.NetworkTransport = networkManager.gameObject.AddComponent<UnityTransport>();
+
+            var networkManagerObject2 = new GameObject(nameof(NestedNetworkObjectPrefabCheck));
+            var networkManager2 = networkManagerObject2.AddComponent<NetworkManager>();
+            networkManager2.NetworkConfig = new NetworkConfig();
+            networkManager2.NetworkConfig.NetworkTransport = networkManager.gameObject.AddComponent<UnityTransport>();
+
+            var object1 = new GameObject("Object 1").AddComponent<NetworkObject>();
+            var object2 = new GameObject("Object 2").AddComponent<NetworkObject>();
+            var object3 = new GameObject("Object 3").AddComponent<NetworkObject>();
+
+            object1.GlobalObjectIdHash = 1;
+            object2.GlobalObjectIdHash = 2;
+            object3.GlobalObjectIdHash = 3;
+
+            var sharedList = ScriptableObject.CreateInstance<NetworkPrefabsList>();
+            sharedList.List.Add(new NetworkPrefab { Prefab = object1.gameObject });
+
+            networkManager.NetworkConfig.Prefabs.NetworkPrefabsLists = new List<NetworkPrefabsList> { sharedList };
+            networkManager2.NetworkConfig.Prefabs.NetworkPrefabsLists = new List<NetworkPrefabsList> { sharedList };
+
+            networkManager.Initialize(true);
+            networkManager2.Initialize(false);
+
+            networkManager.NetworkConfig.Prefabs.Add(new NetworkPrefab { Prefab = object2.gameObject });
+            networkManager2.NetworkConfig.Prefabs.Add(new NetworkPrefab { Prefab = object3.gameObject });
+
+            Assert.IsTrue(networkManager.NetworkConfig.Prefabs.Contains(object1.gameObject));
+            Assert.IsTrue(networkManager2.NetworkConfig.Prefabs.Contains(object1.gameObject));
+            Assert.IsTrue(networkManager.NetworkConfig.Prefabs.Contains(object2.gameObject));
+            Assert.IsFalse(networkManager2.NetworkConfig.Prefabs.Contains(object2.gameObject));
+            Assert.IsTrue(networkManager2.NetworkConfig.Prefabs.Contains(object3.gameObject));
+            Assert.IsFalse(networkManager.NetworkConfig.Prefabs.Contains(object3.gameObject));
+
+            Assert.IsTrue(sharedList.Contains(object1.gameObject));
+            Assert.IsFalse(sharedList.Contains(object2.gameObject));
+            Assert.IsFalse(sharedList.Contains(object3.gameObject));
+        }
+
+        [Test]
+        public void WhenModifyingPrefabListUsingPrefabsListAPI_ModificationIsShared()
+        {
+            // Setup
+            var networkManagerObject = new GameObject(nameof(NestedNetworkObjectPrefabCheck));
+            var networkManager = networkManagerObject.AddComponent<NetworkManager>();
+            networkManager.NetworkConfig = new NetworkConfig();
+            networkManager.NetworkConfig.NetworkTransport = networkManager.gameObject.AddComponent<UnityTransport>();
+
+            var networkManagerObject2 = new GameObject(nameof(NestedNetworkObjectPrefabCheck));
+            var networkManager2 = networkManagerObject2.AddComponent<NetworkManager>();
+            networkManager2.NetworkConfig = new NetworkConfig();
+            networkManager2.NetworkConfig.NetworkTransport = networkManager.gameObject.AddComponent<UnityTransport>();
+
+            var object1 = new GameObject("Object 1").AddComponent<NetworkObject>();
+            var object2 = new GameObject("Object 2").AddComponent<NetworkObject>();
+            var object3 = new GameObject("Object 3").AddComponent<NetworkObject>();
+
+            object1.GlobalObjectIdHash = 1;
+            object2.GlobalObjectIdHash = 2;
+            object3.GlobalObjectIdHash = 3;
+
+            var sharedList = ScriptableObject.CreateInstance<NetworkPrefabsList>();
+            sharedList.List.Add(new NetworkPrefab { Prefab = object1.gameObject });
+
+            networkManager.NetworkConfig.Prefabs.NetworkPrefabsLists = new List<NetworkPrefabsList> { sharedList };
+            networkManager2.NetworkConfig.Prefabs.NetworkPrefabsLists = new List<NetworkPrefabsList> { sharedList };
+
+            networkManager.Initialize(true);
+            networkManager2.Initialize(false);
+
+            networkManager.NetworkConfig.Prefabs.NetworkPrefabsLists[0].Add(new NetworkPrefab { Prefab = object2.gameObject });
+            networkManager2.NetworkConfig.Prefabs.NetworkPrefabsLists[0].Add(new NetworkPrefab { Prefab = object3.gameObject });
+
+            Assert.IsTrue(networkManager.NetworkConfig.Prefabs.Contains(object1.gameObject));
+            Assert.IsTrue(networkManager2.NetworkConfig.Prefabs.Contains(object1.gameObject));
+            Assert.IsTrue(networkManager.NetworkConfig.Prefabs.Contains(object2.gameObject));
+            Assert.IsTrue(networkManager2.NetworkConfig.Prefabs.Contains(object2.gameObject));
+            Assert.IsTrue(networkManager2.NetworkConfig.Prefabs.Contains(object3.gameObject));
+            Assert.IsTrue(networkManager.NetworkConfig.Prefabs.Contains(object3.gameObject));
+
+            Assert.IsTrue(sharedList.Contains(object1.gameObject));
+            Assert.IsTrue(sharedList.Contains(object2.gameObject));
+            Assert.IsTrue(sharedList.Contains(object3.gameObject));
+        }
     }
 }

Tests/Editor/NetworkPrefabProcessorTests.cs

@@ -0,0 +1,90 @@
+using NUnit.Framework;
+using UnityEngine;
+using Unity.Netcode.Editor.Configuration;
+using UnityEditor;
+
+namespace Unity.Netcode.EditorTests
+{
+    public class NetworkPrefabProcessorTests
+    {
+        private NetcodeForGameObjectsProjectSettings m_Settings;
+        private bool m_EditorDefaultPrefabSetting;
+        private string m_EditorDefaultPrefabLocation;
+
+        private GameObject m_Prefab;
+
+        private const string k_PrefabName = "Assets/TestPrefab.prefab";
+        private const string k_DefaultAssetString = "Assets/TestPrefabList.asset";
+
+        [SetUp]
+        public void SetUp()
+        {
+            m_Settings = NetcodeForGameObjectsProjectSettings.instance;
+            m_EditorDefaultPrefabSetting = m_Settings.GenerateDefaultNetworkPrefabs;
+            m_EditorDefaultPrefabLocation = NetworkPrefabProcessor.DefaultNetworkPrefabsPath;
+            NetworkPrefabProcessor.DefaultNetworkPrefabsPath = k_DefaultAssetString;
+        }
+
+        [TearDown]
+        public void TearDown()
+        {
+            m_Settings.GenerateDefaultNetworkPrefabs = m_EditorDefaultPrefabSetting;
+            NetworkPrefabProcessor.DefaultNetworkPrefabsPath = m_EditorDefaultPrefabLocation;
+            AssetDatabase.DeleteAsset(k_PrefabName);
+            AssetDatabase.DeleteAsset(k_DefaultAssetString);
+        }
+
+        [Test]
+        public void WhenGenerateDefaultNetworkPrefabsIsEnabled_AddingAPrefabUpdatesDefaultPrefabList()
+        {
+            var obj = new GameObject("Object");
+            obj.AddComponent<NetworkObject>();
+            m_Settings.GenerateDefaultNetworkPrefabs = true;
+            m_Prefab = PrefabUtility.SaveAsPrefabAsset(obj, k_PrefabName);
+            Object.DestroyImmediate(obj);
+
+            var prefabList = NetworkPrefabProcessor.GetOrCreateNetworkPrefabs(NetworkPrefabProcessor.DefaultNetworkPrefabsPath, out var isNew, false);
+            Assert.IsFalse(isNew);
+            Assert.IsTrue(prefabList.Contains(m_Prefab));
+        }
+
+        [Test]
+        public void WhenGenerateDefaultNetworkPrefabsIsEnabled_RemovingAPrefabUpdatesDefaultPrefabList()
+        {
+            WhenGenerateDefaultNetworkPrefabsIsEnabled_AddingAPrefabUpdatesDefaultPrefabList();
+
+            AssetDatabase.DeleteAsset(k_PrefabName);
+            var prefabList = NetworkPrefabProcessor.GetOrCreateNetworkPrefabs(NetworkPrefabProcessor.DefaultNetworkPrefabsPath, out var isNew, false);
+            Assert.IsFalse(isNew);
+            Assert.IsFalse(prefabList.Contains(m_Prefab));
+        }
+
+        [Test]
+        public void WhenGenerateDefaultNetworkPrefabsIsNotEnabled_AddingAPrefabDoesNotUpdateDefaultPrefabList()
+        {
+            var obj = new GameObject("Object");
+            obj.AddComponent<NetworkObject>();
+            m_Settings.GenerateDefaultNetworkPrefabs = false;
+            m_Prefab = PrefabUtility.SaveAsPrefabAsset(obj, k_PrefabName);
+            Object.DestroyImmediate(obj);
+
+            var prefabList = NetworkPrefabProcessor.GetOrCreateNetworkPrefabs(NetworkPrefabProcessor.DefaultNetworkPrefabsPath, out var isNew, false);
+            Assert.IsTrue(isNew);
+            Assert.IsFalse(prefabList.Contains(m_Prefab));
+        }
+
+        [Test]
+        public void WhenGenerateDefaultNetworkPrefabsIsNotEnabled_RemovingAPrefabDoesNotUpdateDefaultPrefabList()
+        {
+            // Add it with the list enabled, then disable the list. Removing it
+            // should then be nop.
+            WhenGenerateDefaultNetworkPrefabsIsEnabled_AddingAPrefabUpdatesDefaultPrefabList();
+
+            m_Settings.GenerateDefaultNetworkPrefabs = false;
+            AssetDatabase.DeleteAsset(k_PrefabName);
+            var prefabList = NetworkPrefabProcessor.GetOrCreateNetworkPrefabs(NetworkPrefabProcessor.DefaultNetworkPrefabsPath, out var isNew, false);
+            Assert.IsFalse(isNew);
+            Assert.IsTrue(prefabList.Contains(m_Prefab));
+        }
+    }
+}

Tests/Editor/NetworkPrefabProcessorTests.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: 6471efe05b0548ef9d2171e07d4a561b
+timeCreated: 1669140101

Tests/Editor/Transports/BatchedSendQueueTests.cs

@@ -229,6 +229,12 @@ namespace Unity.Netcode.EditorTests
             var writer = new DataStreamWriter(data);
             Assert.AreEqual(messageLength, q.FillWriterWithMessages(ref writer));
             AssertIsTestMessage(data);
+
+            q.Consume(messageLength);
+
+            writer = new DataStreamWriter(data);
+            Assert.AreEqual(messageLength, q.FillWriterWithMessages(ref writer));
+            AssertIsTestMessage(data);
         }
 
         [Test]

Tests/Editor/Transports/UnityTransportTests.cs

@@ -115,13 +115,29 @@ namespace Unity.Netcode.EditorTests
             UnityTransport transport = new GameObject().AddComponent<UnityTransport>();
             transport.Initialize();
 
-            transport.SetConnectionData("127.0.0.", 4242);
+            transport.SetConnectionData("127.0.0.", 4242, "127.0.0.");
             Assert.False(transport.StartServer());
 
             LogAssert.Expect(LogType.Error, "Invalid network endpoint: 127.0.0.:4242.");
-            LogAssert.Expect(LogType.Error, "Server failed to bind");
+#if UTP_TRANSPORT_2_0_ABOVE
+            LogAssert.Expect(LogType.Error, "Socket creation failed (error Unity.Baselib.LowLevel.Binding+Baselib_ErrorState: Invalid argument (0x01000003) <argument name stripped>");
+#endif
+            LogAssert.Expect(LogType.Error, "Server failed to bind. This is usually caused by another process being bound to the same port.");
 
-            transport.SetConnectionData("127.0.0.1", 4242);
+            transport.SetConnectionData("127.0.0.1", 4242, "127.0.0.1");
+            Assert.True(transport.StartServer());
+
+            transport.Shutdown();
+        }
+
+        // Check that leaving all addresses empty is valid.
+        [Test]
+        public void UnityTransport_StartServerWithoutAddresses()
+        {
+            UnityTransport transport = new GameObject().AddComponent<UnityTransport>();
+            transport.Initialize();
+
+            transport.SetConnectionData(string.Empty, 4242);
             Assert.True(transport.StartServer());
 
             transport.Shutdown();

Tests/Runtime/AssemblyInfo.cs

@@ -1,5 +1,11 @@
 using System.Runtime.CompilerServices;
 
-[assembly: InternalsVisibleTo("TestProject.EditorTests")]
+#if UNITY_INCLUDE_TESTS
 [assembly: InternalsVisibleTo("TestProject.RuntimeTests")]
+#if UNITY_EDITOR
+[assembly: InternalsVisibleTo("TestProject.EditorTests")]
+#endif // UNITY_EDITOR
+#if MULTIPLAYER_TOOLS
 [assembly: InternalsVisibleTo("TestProject.ToolsIntegration.RuntimeTests")]
+#endif // MULTIPLAYER_TOOLS
+#endif // UNITY_INCLUDE_TESTS

Tests/Runtime/InvalidConnectionEventsTest.cs

@@ -0,0 +1,167 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text.RegularExpressions;
+using NUnit.Framework;
+using Unity.Collections;
+using UnityEngine.TestTools;
+using Unity.Netcode.TestHelpers.Runtime;
+using UnityEngine;
+using Debug = UnityEngine.Debug;
+
+namespace Unity.Netcode.RuntimeTests
+{
+    public class InvalidConnectionEventsTest : NetcodeIntegrationTest
+    {
+        protected override int NumberOfClients => 1;
+
+        public InvalidConnectionEventsTest() : base(HostOrServer.Server) { }
+
+        private class Hooks<TCatchType> : INetworkHooks
+        {
+            public void OnBeforeSendMessage<T>(ulong clientId, ref T message, NetworkDelivery delivery) where T : INetworkMessage
+            {
+            }
+
+            public void OnAfterSendMessage<T>(ulong clientId, ref T message, NetworkDelivery delivery, int messageSizeBytes) where T : INetworkMessage
+            {
+            }
+
+            public void OnBeforeReceiveMessage(ulong senderId, Type messageType, int messageSizeBytes)
+            {
+            }
+
+            public void OnAfterReceiveMessage(ulong senderId, Type messageType, int messageSizeBytes)
+            {
+            }
+
+            public void OnBeforeSendBatch(ulong clientId, int messageCount, int batchSizeInBytes, NetworkDelivery delivery)
+            {
+            }
+
+            public void OnAfterSendBatch(ulong clientId, int messageCount, int batchSizeInBytes, NetworkDelivery delivery)
+            {
+            }
+
+            public void OnBeforeReceiveBatch(ulong senderId, int messageCount, int batchSizeInBytes)
+            {
+            }
+
+            public void OnAfterReceiveBatch(ulong senderId, int messageCount, int batchSizeInBytes)
+            {
+            }
+
+            public bool OnVerifyCanSend(ulong destinationId, Type messageType, NetworkDelivery delivery)
+            {
+                return true;
+            }
+
+            public bool OnVerifyCanReceive(ulong senderId, Type messageType, FastBufferReader messageContent, ref NetworkContext context)
+            {
+                return true;
+            }
+
+            public void OnBeforeHandleMessage<T>(ref T message, ref NetworkContext context) where T : INetworkMessage
+            {
+                if (typeof(T) == typeof(TCatchType))
+                {
+                    Debug.Log("Woompa");
+                    Assert.Fail($"{typeof(T).Name} was received when it should not have been.");
+                }
+            }
+
+            public void OnAfterHandleMessage<T>(ref T message, ref NetworkContext context) where T : INetworkMessage
+            {
+            }
+        }
+
+        [UnityTest]
+        public IEnumerator WhenSendingConnectionApprovedToAlreadyConnectedClient_ConnectionApprovedMessageIsRejected()
+        {
+            var message = new ConnectionApprovedMessage();
+            m_ServerNetworkManager.SendMessage(ref message, NetworkDelivery.Reliable, m_ClientNetworkManagers[0].LocalClientId);
+
+            // Unnamed message is something to wait for. When this one is received,
+            // we know the above one has also reached its destination.
+            var writer = new FastBufferWriter(1, Allocator.Temp);
+            using (writer)
+            {
+                writer.WriteByteSafe(0);
+                m_ServerNetworkManager.CustomMessagingManager.SendUnnamedMessage(m_ClientNetworkManagers[0].LocalClientId, writer);
+            }
+
+            m_ClientNetworkManagers[0].MessagingSystem.Hook(new Hooks<ConnectionApprovedMessage>());
+
+            LogAssert.Expect(LogType.Error, new Regex($"A {nameof(ConnectionApprovedMessage)} was received from the server when the connection has already been established\\. This should not happen\\."));
+
+            yield return WaitForMessageReceived<UnnamedMessage>(m_ClientNetworkManagers.ToList());
+        }
+
+        [UnityTest]
+        public IEnumerator WhenSendingConnectionRequestToAnyClient_ConnectionRequestMessageIsRejected()
+        {
+            var message = new ConnectionRequestMessage();
+            m_ServerNetworkManager.SendMessage(ref message, NetworkDelivery.Reliable, m_ClientNetworkManagers[0].LocalClientId);
+
+            // Unnamed message is something to wait for. When this one is received,
+            // we know the above one has also reached its destination.
+            var writer = new FastBufferWriter(1, Allocator.Temp);
+            using (writer)
+            {
+                writer.WriteByteSafe(0);
+                m_ServerNetworkManager.CustomMessagingManager.SendUnnamedMessage(m_ClientNetworkManagers[0].LocalClientId, writer);
+            }
+
+            m_ClientNetworkManagers[0].MessagingSystem.Hook(new Hooks<ConnectionRequestMessage>());
+
+            LogAssert.Expect(LogType.Error, new Regex($"A {nameof(ConnectionRequestMessage)} was received from the server on the client side\\. This should not happen\\."));
+
+            yield return WaitForMessageReceived<UnnamedMessage>(m_ClientNetworkManagers.ToList());
+        }
+
+        [UnityTest]
+        public IEnumerator WhenSendingConnectionRequestFromAlreadyConnectedClient_ConnectionRequestMessageIsRejected()
+        {
+            var message = new ConnectionRequestMessage();
+            m_ClientNetworkManagers[0].SendMessage(ref message, NetworkDelivery.Reliable, m_ServerNetworkManager.LocalClientId);
+
+            // Unnamed message is something to wait for. When this one is received,
+            // we know the above one has also reached its destination.
+            var writer = new FastBufferWriter(1, Allocator.Temp);
+            using (writer)
+            {
+                writer.WriteByteSafe(0);
+                m_ClientNetworkManagers[0].CustomMessagingManager.SendUnnamedMessage(m_ServerNetworkManager.LocalClientId, writer);
+            }
+
+            m_ServerNetworkManager.MessagingSystem.Hook(new Hooks<ConnectionRequestMessage>());
+
+            LogAssert.Expect(LogType.Error, new Regex($"A {nameof(ConnectionRequestMessage)} was received from a client when the connection has already been established\\. This should not happen\\."));
+
+            yield return WaitForMessageReceived<UnnamedMessage>(new List<NetworkManager> { m_ServerNetworkManager });
+        }
+
+        [UnityTest]
+        public IEnumerator WhenSendingConnectionApprovedFromAnyClient_ConnectionApprovedMessageIsRejected()
+        {
+            var message = new ConnectionApprovedMessage();
+            m_ClientNetworkManagers[0].SendMessage(ref message, NetworkDelivery.Reliable, m_ServerNetworkManager.LocalClientId);
+
+            // Unnamed message is something to wait for. When this one is received,
+            // we know the above one has also reached its destination.
+            var writer = new FastBufferWriter(1, Allocator.Temp);
+            using (writer)
+            {
+                writer.WriteByteSafe(0);
+                m_ClientNetworkManagers[0].CustomMessagingManager.SendUnnamedMessage(m_ServerNetworkManager.LocalClientId, writer);
+            }
+
+            m_ServerNetworkManager.MessagingSystem.Hook(new Hooks<ConnectionApprovedMessage>());
+
+            LogAssert.Expect(LogType.Error, new Regex($"A {nameof(ConnectionApprovedMessage)} was received from a client on the server side\\. This should not happen\\."));
+
+            yield return WaitForMessageReceived<UnnamedMessage>(new List<NetworkManager> { m_ServerNetworkManager });
+        }
+    }
+}

Tests/Runtime/InvalidConnectionEventsTest.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: c30dd8c697274dd195f0fa8b86a4cf9d
+timeCreated: 1677003739

Tests/Runtime/Metrics/OwnershipChangeMetricsTests.cs

@@ -25,10 +25,10 @@ namespace Unity.Netcode.RuntimeTests.Metrics
             NetcodeIntegrationTestHelpers.MakeNetworkObjectTestPrefab(m_NewNetworkPrefab);
 
             var networkPrefab = new NetworkPrefab { Prefab = gameObject };
-            m_ServerNetworkManager.NetworkConfig.NetworkPrefabs.Add(networkPrefab);
+            m_ServerNetworkManager.NetworkConfig.Prefabs.Add(networkPrefab);
             foreach (var client in m_ClientNetworkManagers)
             {
-                client.NetworkConfig.NetworkPrefabs.Add(networkPrefab);
+                client.NetworkConfig.Prefabs.Add(networkPrefab);
             }
             base.OnServerAndClientsCreated();
         }

Tests/Runtime/NetworkBehaviourGenericTests.cs

@@ -1,5 +1,6 @@
 using System.Collections;
 using UnityEngine;
+using NUnit.Framework;
 using UnityEngine.TestTools;
 using Unity.Netcode.TestHelpers.Runtime;
 using Unity.Netcode.Components;
@@ -147,5 +148,35 @@ namespace Unity.Netcode.RuntimeTests
             // (validating the fix)
             Object.Destroy(parentObject);
         }
+
+        protected override void OnPlayerPrefabGameObjectCreated()
+        {
+            // Adds the SimpleNetworkBehaviour before the NetworkObject
+            // for OnNetworkDespawnInvokedWhenClientDisconnects testing
+            m_PlayerPrefab.AddComponent<SimpleNetworkBehaviour>();
+        }
+
+        /// <summary>
+        /// This validates that upon a client disconnecting, the server-side
+        /// client's player clone will invoke NetworkBehaviour.OnNetworkDespawn
+        /// when the component precedes the NetworkObject component.(PR-2323)
+        /// </summary>
+        [UnityTest]
+        public IEnumerator OnNetworkDespawnInvokedWhenClientDisconnects()
+        {
+            m_AllowServerToStart = true;
+
+            // Now just start the Host
+            yield return StartServerAndClients();
+
+            // Now create and connect a new client
+            yield return CreateAndStartNewClient();
+
+            var serverSidePlayer = m_PlayerNetworkObjects[NetworkManager.ServerClientId][m_ClientNetworkManagers[0].LocalClientId].GetComponent<SimpleNetworkBehaviour>();
+
+            yield return StopOneClient(m_ClientNetworkManagers[0]);
+
+            Assert.True(serverSidePlayer.OnNetworkDespawnCalled, $"Server-side player clone did not invoke OnNetworkDespawn!");
+        }
     }
 }

Tests/Runtime/NetworkBehaviourUpdaterTests.cs

@@ -183,6 +183,11 @@ namespace Unity.Netcode.RuntimeTests
         /// </summary>
         private IEnumerator StartClientsAndServer(bool useHost, int numberOfClients, GameObject prefabObject)
         {
+            void AddNetworkPrefab(NetworkConfig config, NetworkPrefab prefab)
+            {
+                config.Prefabs.Add(prefab);
+            }
+
             // Sanity check to make sure we are not trying to create more clients than we have available to use
             Assert.True(numberOfClients <= m_ClientNetworkManagers.Length);
             m_ActiveClientsForCurrentTest = new List<NetworkManager>();
@@ -194,12 +199,13 @@ namespace Unity.Netcode.RuntimeTests
             }
 
             // Add the prefab to be used for this particular test iteration
-            m_ServerNetworkManager.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Prefab = prefabObject });
+            var np = new NetworkPrefab { Prefab = prefabObject };
+            AddNetworkPrefab(m_ServerNetworkManager.NetworkConfig, np);
             m_ServerNetworkManager.NetworkConfig.TickRate = 30;
             foreach (var clientManager in m_ActiveClientsForCurrentTest)
             {
                 m_ServerNetworkManager.NetworkConfig.TickRate = 30;
-                clientManager.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Prefab = prefabObject });
+                AddNetworkPrefab(clientManager.NetworkConfig, np);
             }
 
             // Now spin everything up normally

Tests/Runtime/NetworkObject/NetworkObjectNetworkClientOwnedObjectsTests.cs

@@ -15,32 +15,18 @@ namespace Unity.Netcode.RuntimeTests
         }
 
         protected override int NumberOfClients => 1;
-        private NetworkPrefab m_NetworkPrefab;
+        private GameObject m_NetworkObject;
+
         protected override void OnServerAndClientsCreated()
         {
-            // create prefab
-            var gameObject = new GameObject("ClientOwnedObject");
-            var networkObject = gameObject.AddComponent<NetworkObject>();
-            gameObject.AddComponent<DummyNetworkBehaviour>();
-            NetcodeIntegrationTestHelpers.MakeNetworkObjectTestPrefab(networkObject);
-
-            m_NetworkPrefab = (new NetworkPrefab()
-            {
-                Prefab = gameObject
-            });
-
-            m_ServerNetworkManager.NetworkConfig.NetworkPrefabs.Add(m_NetworkPrefab);
-
-            foreach (var client in m_ClientNetworkManagers)
-            {
-                client.NetworkConfig.NetworkPrefabs.Add(m_NetworkPrefab);
-            }
+            m_NetworkObject = CreateNetworkObjectPrefab("ClientOwnedObject");
+            m_NetworkObject.gameObject.AddComponent<DummyNetworkBehaviour>();
         }
 
         [UnityTest]
         public IEnumerator ChangeOwnershipOwnedObjectsAddTest()
         {
-            NetworkObject serverObject = Object.Instantiate(m_NetworkPrefab.Prefab).GetComponent<NetworkObject>();
+            NetworkObject serverObject = m_NetworkObject.GetComponent<NetworkObject>();
             serverObject.NetworkManagerOwner = m_ServerNetworkManager;
             serverObject.Spawn();
 
@@ -64,7 +50,7 @@ namespace Unity.Netcode.RuntimeTests
         [UnityTest]
         public IEnumerator WhenOwnershipIsChanged_OwnershipValuesUpdateCorrectly()
         {
-            NetworkObject serverObject = Object.Instantiate(m_NetworkPrefab.Prefab).GetComponent<NetworkObject>();
+            NetworkObject serverObject = m_NetworkObject.GetComponent<NetworkObject>();
             serverObject.NetworkManagerOwner = m_ServerNetworkManager;
             serverObject.Spawn();
 

Tests/Runtime/NetworkObject/NetworkObjectOnNetworkDespawnTests.cs

@@ -40,21 +40,9 @@ namespace Unity.Netcode.RuntimeTests
         {
             Assert.IsTrue(NetcodeIntegrationTestHelpers.Create(1, out m_ServerHost, out m_Clients));
 
-            m_ObjectToSpawn = new GameObject();
-            m_NetworkObject = m_ObjectToSpawn.AddComponent<NetworkObject>();
+            m_ObjectToSpawn = NetcodeIntegrationTestHelpers.CreateNetworkObjectPrefab(nameof(NetworkObjectOnNetworkDespawnTests), m_ServerHost, m_Clients);
             m_ObjectToSpawn.AddComponent<OnNetworkDespawnTestComponent>();
-
-            // Make it a prefab
-            NetcodeIntegrationTestHelpers.MakeNetworkObjectTestPrefab(m_NetworkObject);
-
-            var networkPrefab = new NetworkPrefab();
-            networkPrefab.Prefab = m_ObjectToSpawn;
-            m_ServerHost.NetworkConfig.NetworkPrefabs.Add(networkPrefab);
-
-            foreach (var client in m_Clients)
-            {
-                client.NetworkConfig.NetworkPrefabs.Add(networkPrefab);
-            }
+            m_NetworkObject = m_ObjectToSpawn.GetComponent<NetworkObject>();
 
             yield return null;
         }
@@ -130,4 +118,3 @@ namespace Unity.Netcode.RuntimeTests
         }
     }
 }
-

Tests/Runtime/NetworkObject/NetworkObjectSpawnManyObjectsTests.cs

@@ -39,10 +39,10 @@ namespace Unity.Netcode.RuntimeTests
 
             m_PrefabToSpawn = new NetworkPrefab() { Prefab = gameObject };
 
-            m_ServerNetworkManager.NetworkConfig.NetworkPrefabs.Add(m_PrefabToSpawn);
+            m_ServerNetworkManager.NetworkConfig.Prefabs.Add(m_PrefabToSpawn);
             foreach (var client in m_ClientNetworkManagers)
             {
-                client.NetworkConfig.NetworkPrefabs.Add(m_PrefabToSpawn);
+                client.NetworkConfig.Prefabs.Add(m_PrefabToSpawn);
             }
         }
 

Tests/Runtime/NetworkObject/NetworkObjectSynchronizationTests.cs

@@ -78,13 +78,13 @@ namespace Unity.Netcode.RuntimeTests
         {
             networkManager.NetworkConfig.PlayerPrefab = m_PlayerPrefab;
             networkManager.NetworkConfig.EnsureNetworkVariableLengthSafety = m_VariableLengthSafety == VariableLengthSafety.EnabledNetVarSafety;
-            foreach (var networkPrefab in m_ServerNetworkManager.NetworkConfig.NetworkPrefabs)
+            foreach (var networkPrefab in m_ServerNetworkManager.NetworkConfig.Prefabs.Prefabs)
             {
                 // To simulate a failure, we exclude the m_InValidNetworkPrefab from the connecting
                 // client's side.
                 if (networkPrefab.Prefab.name != m_InValidNetworkPrefab.name)
                 {
-                    networkManager.NetworkConfig.NetworkPrefabs.Add(networkPrefab);
+                    networkManager.NetworkConfig.Prefabs.Add(networkPrefab);
                 }
             }
             // Disable forcing the same prefabs to avoid failed connections

Tests/Runtime/NetworkPrefabHandlerTests.cs

@@ -29,7 +29,7 @@ namespace Unity.Netcode.RuntimeTests
         }
 
         /// <summary>
-        /// Tests the NetwokConfig NetworkPrefabs initialization during NetworkManager's Init method to make sure that
+        /// Tests the NetwokConfig NetworkPrefabsList initialization during NetworkManager's Init method to make sure that
         /// it will still initialize but remove the invalid prefabs
         /// </summary>
         [Test]
@@ -37,34 +37,34 @@ namespace Unity.Netcode.RuntimeTests
         {
 
             // Add null entry
-            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.NetworkPrefabs.Add(null);
+            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.Prefabs.Add(null);
 
             // Add a NetworkPrefab with no prefab
-            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab());
+            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.Prefabs.Add(new NetworkPrefab());
 
             // Add a NetworkPrefab override with an invalid hash
-            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Hash, SourceHashToOverride = 0 });
+            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.Prefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Hash, SourceHashToOverride = 0 });
 
             // Add a NetworkPrefab override with a valid hash but an invalid target prefab
-            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Hash, SourceHashToOverride = 654321, OverridingTargetPrefab = null });
+            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.Prefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Hash, SourceHashToOverride = 654321, OverridingTargetPrefab = null });
 
             // Add a NetworkPrefab override with a valid hash to override but an invalid target prefab
-            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Prefab, SourceHashToOverride = 654321, OverridingTargetPrefab = null });
+            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.Prefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Prefab, SourceHashToOverride = 654321, OverridingTargetPrefab = null });
 
             // Add a NetworkPrefab override with an invalid source prefab to override
-            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Prefab, SourcePrefabToOverride = null });
+            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.Prefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Prefab, SourcePrefabToOverride = null });
 
             // Add a NetworkPrefab override with a valid source prefab to override but an invalid target prefab
-            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Prefab, SourcePrefabToOverride = MakeValidNetworkPrefab(), OverridingTargetPrefab = null });
+            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.Prefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Prefab, SourcePrefabToOverride = MakeValidNetworkPrefab(), OverridingTargetPrefab = null });
 
             // Add a valid prefab
-            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Prefab = MakeValidNetworkPrefab() });
+            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.Prefabs.Add(new NetworkPrefab() { Prefab = MakeValidNetworkPrefab() });
 
             // Add a NetworkPrefab override with a valid hash and valid target prefab
-            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Hash, SourceHashToOverride = 11111111, OverridingTargetPrefab = MakeValidNetworkPrefab() });
+            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.Prefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Hash, SourceHashToOverride = 11111111, OverridingTargetPrefab = MakeValidNetworkPrefab() });
 
             // Add a NetworkPrefab override with a valid prefab and valid target prefab
-            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Prefab, SourcePrefabToOverride = MakeValidNetworkPrefab(), OverridingTargetPrefab = MakeValidNetworkPrefab() });
+            NetworkManagerHelper.NetworkManagerObject.NetworkConfig.Prefabs.Add(new NetworkPrefab() { Override = NetworkPrefabOverride.Prefab, SourcePrefabToOverride = MakeValidNetworkPrefab(), OverridingTargetPrefab = MakeValidNetworkPrefab() });
 
             var exceptionOccurred = false;
             try
@@ -79,7 +79,7 @@ namespace Unity.Netcode.RuntimeTests
             Assert.False(exceptionOccurred);
 
             // In the end we should only have 3 valid registered network prefabs
-            Assert.True(NetworkManagerHelper.NetworkManagerObject.NetworkConfig.NetworkPrefabOverrideLinks.Count == 3);
+            Assert.True(NetworkManagerHelper.NetworkManagerObject.NetworkConfig.Prefabs.NetworkPrefabOverrideLinks.Count == 3);
         }
 
         private const string k_PrefabObjectName = "NetworkPrefabHandlerTestObject";

Tests/Runtime/NetworkShowHideTests.cs

@@ -14,6 +14,8 @@ namespace Unity.Netcode.RuntimeTests
         public static ulong ClientIdToTarget;
         public static bool Silent;
         public static int ValueAfterOwnershipChange = 0;
+        public static Dictionary<ulong, ShowHideObject> ObjectsPerClientId = new Dictionary<ulong, ShowHideObject>();
+        public static List<ulong> ClientIdsRpcCalledOn;
 
         public static NetworkObject GetNetworkObjectById(ulong networkObjectId)
         {
@@ -44,6 +46,15 @@ namespace Unity.Netcode.RuntimeTests
                 Debug.Assert(MyListSetOnSpawn[0] == 45);
             }
 
+            if (ObjectsPerClientId.ContainsKey(NetworkManager.LocalClientId))
+            {
+                ObjectsPerClientId[NetworkManager.LocalClientId] = this;
+            }
+            else
+            {
+                ObjectsPerClientId.Add(NetworkManager.LocalClientId, this);
+            }
+
             base.OnNetworkSpawn();
         }
 
@@ -59,6 +70,7 @@ namespace Unity.Netcode.RuntimeTests
         public NetworkVariable<int> MyNetworkVariable;
         public NetworkList<int> MyListSetOnSpawn;
         public NetworkVariable<int> MyOwnerReadNetworkVariable;
+        public NetworkList<int> MyList;
         static public NetworkManager NetworkManagerOfInterest;
 
         internal static int GainOwnershipCount = 0;
@@ -70,6 +82,7 @@ namespace Unity.Netcode.RuntimeTests
             MyNetworkVariable.OnValueChanged += Changed;
 
             MyListSetOnSpawn = new NetworkList<int>();
+            MyList = new NetworkList<int>();
 
             MyOwnerReadNetworkVariable = new NetworkVariable<int>(readPerm: NetworkVariableReadPermission.Owner);
             MyOwnerReadNetworkVariable.OnValueChanged += OwnerReadChanged;
@@ -96,11 +109,26 @@ namespace Unity.Netcode.RuntimeTests
                 Debug.Log($"Value changed from {before} to {after}");
             }
         }
+
+        [ClientRpc]
+        public void SomeRandomClientRPC()
+        {
+            Debug.Log($"RPC called {NetworkManager.LocalClientId}");
+            if (ClientIdsRpcCalledOn != null)
+            {
+                ClientIdsRpcCalledOn.Add(NetworkManager.LocalClientId);
+            }
+        }
+
+        public void TriggerRpc()
+        {
+            SomeRandomClientRPC();
+        }
     }
 
     public class NetworkShowHideTests : NetcodeIntegrationTest
     {
-        protected override int NumberOfClients => 2;
+        protected override int NumberOfClients => 4;
 
         private ulong m_ClientId0;
         private GameObject m_PrefabToSpawn;
@@ -124,7 +152,7 @@ namespace Unity.Netcode.RuntimeTests
             int count = 0;
             do
             {
-                yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
+                yield return WaitForTicks(m_ServerNetworkManager, 5);
                 count++;
 
                 if (count > 20)
@@ -240,11 +268,11 @@ namespace Unity.Netcode.RuntimeTests
                 // hide them on one client
                 Show(mode == 0, false);
 
-                yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
+                yield return WaitForTicks(m_ServerNetworkManager, 5);
 
                 m_NetSpawnedObject1.GetComponent<ShowHideObject>().MyNetworkVariable.Value = 3;
 
-                yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
+                yield return WaitForTicks(m_ServerNetworkManager, 5);
 
                 // verify they got hidden
                 yield return CheckVisible(false);
@@ -286,10 +314,10 @@ namespace Unity.Netcode.RuntimeTests
                 Show(mode == 0, false);
                 Show(mode == 0, true);
 
-                yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
+                yield return WaitForTicks(m_ServerNetworkManager, 5);
                 yield return WaitForConditionOrTimeOut(RefreshNetworkObjects);
                 AssertOnTimeout($"Could not refresh all NetworkObjects!");
-                yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
+                yield return WaitForTicks(m_ServerNetworkManager, 5);
 
                 // verify they become visible
                 yield return CheckVisible(true);
@@ -315,7 +343,7 @@ namespace Unity.Netcode.RuntimeTests
             m_NetSpawnedObject1.NetworkHide(m_ClientId0);
             m_NetSpawnedObject1.Despawn();
 
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
+            yield return WaitForTicks(m_ServerNetworkManager, 5);
 
             LogAssert.NoUnexpectedReceived();
         }
@@ -372,7 +400,7 @@ namespace Unity.Netcode.RuntimeTests
             m_NetSpawnedObject1.GetComponent<ShowHideObject>().MyOwnerReadNetworkVariable.Value++;
 
             // wait for three ticks
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 3);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
 
             // check we'll actually be changing owners
             Assert.False(ShowHideObject.ClientTargetedNetworkObjects[0].OwnerClientId == m_ClientNetworkManagers[0].LocalClientId);
@@ -384,8 +412,8 @@ namespace Unity.Netcode.RuntimeTests
             m_NetSpawnedObject1.ChangeOwnership(m_ClientNetworkManagers[0].LocalClientId);
 
             // wait three ticks
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 3);
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ClientNetworkManagers[0], 3);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
+            yield return WaitForTicks(m_ClientNetworkManagers[0], 3);
 
             // verify ownership changed
             Assert.True(ShowHideObject.ClientTargetedNetworkObjects[0].OwnerClientId == m_ClientNetworkManagers[0].LocalClientId);
@@ -394,5 +422,155 @@ namespace Unity.Netcode.RuntimeTests
             Assert.True(ShowHideObject.ValueAfterOwnershipChange == 1);
         }
 
+        private string Display(NetworkList<int> list)
+        {
+            string message = "";
+            foreach (var i in list)
+            {
+                message += $"{i}, ";
+            }
+
+            return message;
+        }
+
+        private void Compare(NetworkList<int> list1, NetworkList<int> list2)
+        {
+            if (list1.Count != list2.Count)
+            {
+                string message = $"{Display(list1)} versus {Display(list2)}";
+                Debug.Log(message);
+            }
+            else
+            {
+                for (var i = 0; i < list1.Count; i++)
+                {
+                    if (list1[i] != list2[i])
+                    {
+                        string message = $"{Display(list1)} versus {Display(list2)}";
+                        Debug.Log(message);
+                        break;
+                    }
+                }
+            }
+
+            Debug.Assert(list1.Count == list2.Count);
+        }
+
+        private IEnumerator HideThenShowAndHideThenModifyAndShow()
+        {
+            Debug.Log("Hiding");
+            // hide
+            m_NetSpawnedObject1.NetworkHide(1);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
+            yield return WaitForTicks(m_ClientNetworkManagers[0], 3);
+
+            Debug.Log("Showing and Hiding");
+            // show and hide
+            m_NetSpawnedObject1.NetworkShow(1);
+            m_NetSpawnedObject1.NetworkHide(1);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
+            yield return WaitForTicks(m_ClientNetworkManagers[0], 3);
+
+            Debug.Log("Modifying and Showing");
+            // modify and show
+            m_NetSpawnedObject1.GetComponent<ShowHideObject>().MyList.Add(5);
+            m_NetSpawnedObject1.NetworkShow(1);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
+            yield return WaitForTicks(m_ClientNetworkManagers[0], 3);
+        }
+
+
+        private IEnumerator HideThenModifyAndShow()
+        {
+            // hide
+            m_NetSpawnedObject1.NetworkHide(1);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
+
+            // modify
+            m_NetSpawnedObject1.GetComponent<ShowHideObject>().MyList.Add(5);
+            // show
+            m_NetSpawnedObject1.NetworkShow(1);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
+            yield return WaitForTicks(m_ClientNetworkManagers[0], 3);
+
+        }
+
+        private IEnumerator HideThenShowAndModify()
+        {
+            // hide
+            m_NetSpawnedObject1.NetworkHide(1);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
+
+            // show
+            m_NetSpawnedObject1.NetworkShow(1);
+            // modify
+            m_NetSpawnedObject1.GetComponent<ShowHideObject>().MyList.Add(5);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
+            yield return WaitForTicks(m_ClientNetworkManagers[0], 3);
+        }
+
+        private IEnumerator HideThenShowAndRPC()
+        {
+            // hide
+            m_NetSpawnedObject1.NetworkHide(1);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
+
+            // show
+            m_NetSpawnedObject1.NetworkShow(1);
+            m_NetSpawnedObject1.GetComponent<ShowHideObject>().TriggerRpc();
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
+        }
+
+        [UnityTest]
+        public IEnumerator NetworkShowHideAroundListModify()
+        {
+            ShowHideObject.ClientTargetedNetworkObjects.Clear();
+            ShowHideObject.ClientIdToTarget = m_ClientNetworkManagers[1].LocalClientId;
+            ShowHideObject.Silent = true;
+
+            var spawnedObject1 = SpawnObject(m_PrefabToSpawn, m_ServerNetworkManager);
+            m_NetSpawnedObject1 = spawnedObject1.GetComponent<NetworkObject>();
+
+            // wait for host to have spawned and gained ownership
+            while (ShowHideObject.GainOwnershipCount == 0)
+            {
+                yield return new WaitForSeconds(0.0f);
+            }
+
+            for (int i = 0; i < 4; i++)
+            {
+                // wait for three ticks
+                yield return WaitForTicks(m_ServerNetworkManager, 3);
+                yield return WaitForTicks(m_ClientNetworkManagers[0], 3);
+
+                switch (i)
+                {
+                    case 0:
+                        Debug.Log("Running HideThenModifyAndShow");
+                        yield return HideThenModifyAndShow();
+                        break;
+                    case 1:
+                        Debug.Log("Running HideThenShowAndModify");
+                        yield return HideThenShowAndModify();
+                        break;
+                    case 2:
+                        Debug.Log("Running HideThenShowAndHideThenModifyAndShow");
+                        yield return HideThenShowAndHideThenModifyAndShow();
+                        break;
+                    case 3:
+                        Debug.Log("Running HideThenShowAndRPC");
+                        ShowHideObject.ClientIdsRpcCalledOn = new List<ulong>();
+                        yield return HideThenShowAndRPC();
+                        // Provide enough time for slower systems or VM systems possibly under a heavy load could fail on this test
+                        yield return WaitForConditionOrTimeOut(() => ShowHideObject.ClientIdsRpcCalledOn.Count == NumberOfClients + 1);
+                        AssertOnTimeout($"Timed out waiting for ClientIdsRpcCalledOn.Count ({ShowHideObject.ClientIdsRpcCalledOn.Count}) to equal ({NumberOfClients + 1})!");
+                        break;
+
+                }
+
+                Compare(ShowHideObject.ObjectsPerClientId[0].MyList, ShowHideObject.ObjectsPerClientId[1].MyList);
+                Compare(ShowHideObject.ObjectsPerClientId[0].MyList, ShowHideObject.ObjectsPerClientId[2].MyList);
+            }
+        }
     }
 }

Tests/Runtime/NetworkTransform/NetworkTransformTests.cs

@@ -402,7 +402,7 @@ namespace Unity.Netcode.RuntimeTests
 
         protected override void OnNewClientCreated(NetworkManager networkManager)
         {
-            networkManager.NetworkConfig.NetworkPrefabs = m_ServerNetworkManager.NetworkConfig.NetworkPrefabs;
+            networkManager.NetworkConfig.Prefabs = m_ServerNetworkManager.NetworkConfig.Prefabs;
             base.OnNewClientCreated(networkManager);
         }
 

Tests/Runtime/NetworkVariableTests.cs

@@ -236,7 +236,7 @@ namespace Unity.Netcode.RuntimeTests
             int clientManagerIndex = m_ClientNetworkManagers.Length - 1;
             var newOwnerClientId = m_ClientNetworkManagers[clientManagerIndex].LocalClientId;
             testObjServer.ChangeOwnership(newOwnerClientId);
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 2);
+            yield return WaitForTicks(m_ServerNetworkManager, 2);
 
             yield return WaitForOwnerWritableAreEqualOnAll();
 
@@ -269,7 +269,7 @@ namespace Unity.Netcode.RuntimeTests
             int clientManagerIndex = m_ClientNetworkManagers.Length - 1;
             var newOwnerClientId = m_ClientNetworkManagers[clientManagerIndex].LocalClientId;
             testObjServer.ChangeOwnership(newOwnerClientId);
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 2);
+            yield return WaitForTicks(m_ServerNetworkManager, 2);
 
             yield return WaitForOwnerWritableAreEqualOnAll();
 
@@ -301,7 +301,7 @@ namespace Unity.Netcode.RuntimeTests
             int clientManagerIndex = m_ClientNetworkManagers.Length - 1;
             var newOwnerClientId = m_ClientNetworkManagers[clientManagerIndex].LocalClientId;
             testObjServer.ChangeOwnership(newOwnerClientId);
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 2);
+            yield return WaitForTicks(m_ServerNetworkManager, 2);
 
             yield return WaitForServerWritableAreEqualOnAll();
 
@@ -333,7 +333,7 @@ namespace Unity.Netcode.RuntimeTests
             int clientManagerIndex = m_ClientNetworkManagers.Length - 1;
             var newOwnerClientId = m_ClientNetworkManagers[clientManagerIndex].LocalClientId;
             testObjServer.ChangeOwnership(newOwnerClientId);
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 2);
+            yield return WaitForTicks(m_ServerNetworkManager, 2);
 
             yield return WaitForOwnerWritableAreEqualOnAll();
 

Tests/Runtime/OwnerModifiedTests.cs

@@ -91,10 +91,10 @@ namespace Unity.Netcode.RuntimeTests
                 ownerModLastClient.NetworkUpdateStageToCheck = (NetworkUpdateStage)updateLoopType;
                 Debug.Log($"Testing Update Stage: {ownerModLastClient.NetworkUpdateStageToCheck}");
                 ownerModLastClient.AddValues = true;
-                yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
+                yield return WaitForTicks(m_ServerNetworkManager, 5);
             }
 
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
+            yield return WaitForTicks(m_ServerNetworkManager, 5);
 
             // We'll have at least one update per stage per client, if all goes well.
             Assert.True(OwnerModifiedObject.Updates > 20);

Tests/Runtime/OwnerPermissionTests.cs

@@ -197,9 +197,9 @@ namespace Unity.Netcode.RuntimeTests
                     // Verify client-owned networkList can only be written by owner
                     Debug.Assert(gotException == (clientWriting != objectIndex));
 
-                    yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
-                    yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ClientNetworkManagers[0], 5);
-                    yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ClientNetworkManagers[1], 5);
+                    yield return WaitForTicks(m_ServerNetworkManager, 5);
+                    yield return WaitForTicks(m_ClientNetworkManagers[0], 5);
+                    yield return WaitForTicks(m_ClientNetworkManagers[1], 5);
 
                     OwnerPermissionObject.VerifyConsistency();
                 }

Tests/Runtime/Physics/NetworkRigidbody2DTest.cs

@@ -53,7 +53,7 @@ namespace Unity.Netcode.RuntimeTests
             Assert.IsNotNull(serverPlayer);
             Assert.IsNotNull(clientPlayer);
 
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
+            yield return WaitForTicks(m_ServerNetworkManager, 5);
 
             // server rigidbody has authority and should have a kinematic mode of false
             Assert.True(serverPlayer.GetComponent<Rigidbody2D>().isKinematic == Kinematic);
@@ -66,12 +66,12 @@ namespace Unity.Netcode.RuntimeTests
             // despawn the server player, (but keep it around on the server)
             serverPlayer.GetComponent<NetworkObject>().Despawn(false);
 
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
+            yield return WaitForTicks(m_ServerNetworkManager, 5);
 
             // This should equal Kinematic
             Assert.IsTrue(serverPlayer.GetComponent<Rigidbody2D>().isKinematic == Kinematic);
 
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 5);
+            yield return WaitForTicks(m_ServerNetworkManager, 5);
 
             Assert.IsTrue(clientPlayer == null); // safety check that object is actually despawned.
         }

Tests/Runtime/Physics/NetworkRigidbodyTest.cs

@@ -40,7 +40,7 @@ namespace Unity.Netcode.RuntimeTests
             Assert.IsNotNull(serverPlayer, "serverPlayer is not null");
             Assert.IsNotNull(clientPlayer, "clientPlayer is not null");
 
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 3);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
 
             // server rigidbody has authority and should not be kinematic
             Assert.True(serverPlayer.GetComponent<Rigidbody>().isKinematic == false, "serverPlayer kinematic");
@@ -53,12 +53,12 @@ namespace Unity.Netcode.RuntimeTests
             // despawn the server player (but keep it around on the server)
             serverPlayer.GetComponent<NetworkObject>().Despawn(false);
 
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 3);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
 
             // When despawned, we should always be kinematic (i.e. don't apply physics when despawned)
             Assert.IsTrue(serverPlayer.GetComponent<Rigidbody>().isKinematic == true, "serverPlayer second kinematic");
 
-            yield return NetcodeIntegrationTestHelpers.WaitForTicks(m_ServerNetworkManager, 3);
+            yield return WaitForTicks(m_ServerNetworkManager, 3);
 
             Assert.IsTrue(clientPlayer == null, "clientPlayer being null"); // safety check that object is actually despawned.
         }

Tests/Runtime/RpcManyClientsTests.cs

@@ -62,10 +62,10 @@ namespace Unity.Netcode.RuntimeTests
             prefabToSpawn.AddComponent(type);
             var networkObjectPrefab = prefabToSpawn.AddComponent<NetworkObject>();
             NetcodeIntegrationTestHelpers.MakeNetworkObjectTestPrefab(networkObjectPrefab);
-            m_ServerNetworkManager.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Prefab = prefabToSpawn });
+            m_ServerNetworkManager.NetworkConfig.Prefabs.Add(new NetworkPrefab() { Prefab = prefabToSpawn });
             foreach (var clientNetworkManager in m_ClientNetworkManagers)
             {
-                clientNetworkManager.NetworkConfig.NetworkPrefabs.Add(new NetworkPrefab() { Prefab = prefabToSpawn });
+                clientNetworkManager.NetworkConfig.Prefabs.Add(new NetworkPrefab() { Prefab = prefabToSpawn });
             }
             return prefabToSpawn;
         }

package.json

@@ -2,20 +2,23 @@
   "name": "com.unity.netcode.gameobjects",
   "displayName": "Netcode for GameObjects",
   "description": "Netcode for GameObjects is a high-level netcode SDK that provides networking capabilities to GameObject/MonoBehaviour workflows within Unity and sits on top of underlying transport layer.",
-  "version": "1.2.0",
+  "version": "1.3.1",
   "unity": "2020.3",
   "dependencies": {
     "com.unity.nuget.mono-cecil": "1.10.1",
-    "com.unity.transport": "1.3.0"
+    "com.unity.transport": "1.3.3"
+  },
+  "_upm": {
+    "changelog": "### Added\n\n- Added detection and graceful handling of corrupt packets for additional safety. (#2419)\n\n### Changed\n\n- The UTP component UI has been updated to be more user-friendly for new users by adding a simple toggle to switch between local-only (127.0.0.1) and remote (0.0.0.0) binding modes, using the toggle \"Allow Remote Connections\" (#2408)\n- Updated `UnityTransport` dependency on `com.unity.transport` to 1.3.3. (#2450)\n- `NetworkShow()` of `NetworkObject`s are delayed until the end of the frame to ensure consistency of delta-driven variables like `NetworkList`.\n- Dirty `NetworkObject` are reset at end-of-frame and not at serialization time.\n- `NetworkHide()` of an object that was just `NetworkShow()`n produces a warning, as remote clients will _not_ get a spawn/despawn pair.\n- Renamed the NetworkTransform.SetState parameter `shouldGhostsInterpolate` to `teleportDisabled` for better clarity of what that parameter does. (#2228)\n- Network prefabs are now stored in a ScriptableObject that can be shared between NetworkManagers, and have been exposed for public access. By default, a Default Prefabs List is created that contains all NetworkObject prefabs in the project, and new NetworkManagers will default to using that unless that option is turned off in the Netcode for GameObjects settings. Existing NetworkManagers will maintain their existing lists, which can be migrated to the new format via a button in their inspector. (#2322)\n\n### Fixed\n\n- Fixed issue where changes to a layer's weight would not synchronize unless a state transition was occurring.(#2399)\n- Fixed issue where `NetworkManager.LocalClientId` was returning the `NetworkTransport.ServerClientId` as opposed to the `NetworkManager.m_LocalClientId`. (#2398)\n- Fixed issue where a dynamically spawned `NetworkObject` parented under an in-scene placed `NetworkObject` would have its `InScenePlaced` value changed to `true`. This would result in a soft synchronization error for late joining clients. (#2396)\n- Fixed a UTP test that was failing when you install Unity Transport package 2.0.0 or newer. (#2347)\n- Fixed issue where `NetcodeSettingsProvider` would throw an exception in Unity 2020.3.x versions. (#2345)\n- Fixed server side issue where, depending upon component ordering, some NetworkBehaviour components might not have their OnNetworkDespawn method invoked if the client side disconnected. (#2323)\n- Fixed a case where data corruption could occur when using UnityTransport when reaching a certain level of send throughput. (#2332)\n- Fixed an issue in `UnityTransport` where an exception would be thrown if starting a Relay host/server on WebGL. This exception should only be thrown if using direct connections (where WebGL can't act as a host/server). (#2321)\n- Fixed `NetworkAnimator` issue where it was not checking for `AnimatorStateTtansition.destinationStateMachine` and any possible sub-states defined within it. (#2309)\n- Fixed `NetworkAnimator` issue where the host client was receiving the ClientRpc animation updates when the host was the owner.(#2309)\n- Fixed `NetworkAnimator` issue with using pooled objects and when specific properties are cleaned during despawn and destroy.(#2309)\n- Fixed issue where `NetworkAnimator` was checking for animation changes when the associated `NetworkObject` was not spawned.(#2309)\n- Corrected an issue with the documentation for BufferSerializer (#2401)"
   },
   "upmCi": {
-    "footprint": "4160b9a4b03a930793225fd4767f2b00fee62c79"
+    "footprint": "edebf4ce36d2ecd3e2a7632dbf88da8cbc89aa50"
   },
-  "documentationUrl": "https://docs.unity3d.com/Packages/com.unity.netcode.gameobjects@1.2/manual/index.html",
+  "documentationUrl": "https://docs.unity3d.com/Packages/com.unity.netcode.gameobjects@1.3/manual/index.html",
   "repository": {
     "url": "https://github.com/Unity-Technologies/com.unity.netcode.gameobjects.git",
     "type": "git",
-    "revision": "789f0930ead8e5ba27e123323f407d6f3393aa7b"
+    "revision": "469b46fabe1a78032a31ab04a15490a6912dadfb"
   },
   "samples": [
     {