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)

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

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