fix

Fixing issue where we were sending scene migration notifications when migrating into the DDOL.
Fixing issue where if a client detected a changed scene but had no scene change to send (later) it would throw and exception and cause a memory leak.

Author: NoelStephensUnity

com.unity.netcode.gameobjects/Runtime/Core/NetworkObject.cs

@@ -3655,11 +3655,18 @@ internal void SceneChangedUpdate(Scene scene, bool notify = false)
                 return;
             }
 
+            // Don't create notification if there is a scene event in progress.
             if (NetworkManagerOwner.SceneManager.IsSceneEventInProgress())
             {
                 return;
             }
 
+            // Don't  create notification if the scene is the DDOL.
+            if (scene == NetworkManager.SceneManager.DontDestroyOnLoadScene)
+            {
+                return;
+            }
+
             SceneOriginHandle = scene.handle;
 
             // non-authority needs to update the NetworkSceneHandle

com.unity.netcode.gameobjects/Runtime/SceneManagement/NetworkSceneManager.cs

@@ -2890,7 +2890,6 @@ internal bool IsSceneUnloading(NetworkObject networkObject)
         /// </summary>
         internal void NotifyNetworkObjectSceneChanged(NetworkObject networkObject)
         {
-            Debug.Log($"{networkObject.name} changed scene to {networkObject.gameObject.scene.name}!");
             if (networkObject.NetworkManagerOwner != NetworkManager)
             {
                 Debug.Log($"!!!!!!!!!!!!! Integration test is registering for scene migration for instances outside of the bounds of this NetworkManager context !!!!!!!!!!!!!");
@@ -3060,7 +3059,14 @@ internal void CheckForAndSendNetworkObjectSceneChanged()
             // Some NetworkObjects still exist, send the message
             var sceneEvent = BeginSceneEvent();
             sceneEvent.SceneEventType = SceneEventType.ObjectSceneChanged;
-            SendSceneEventData(sceneEvent.SceneEventId, NetworkManager.ConnectedClientsIds.Where(c => c != NetworkManager.LocalClientId).ToArray());
+            try
+            {
+                SendSceneEventData(sceneEvent.SceneEventId, NetworkManager.ConnectedClientsIds.Where(c => c != NetworkManager.LocalClientId).ToArray());
+            }
+            catch (Exception ex)
+            {
+                Debug.LogException(ex);
+            }
             ObjectsMigratedIntoNewScene.Clear();
             EndSceneEvent(sceneEvent.SceneEventId);
         }

testproject/Assets/Tests/Runtime/NetworkSceneManager/NetworkObjectSceneMigrationTests.cs

@@ -286,6 +286,12 @@ protected override void OnNewClientCreated(NetworkManager networkManager)
             base.OnNewClientCreated(networkManager);
         }
 
+        private void SetActiveScene(Scene scene)
+        {
+            Debug.Log($"[Previous = {SceneManager.GetActiveScene().name}][New = {scene.name}] Changing the active scene!");
+            SceneManager.SetActiveScene(scene);
+        }
+
         /// <summary>
         /// Integration test to verify changing the currently active scene
         /// will migrate NetworkObjects with ActiveSceneSynchronization set
@@ -311,7 +317,7 @@ public IEnumerator ActiveSceneSynchronizationTest()
             authority.SceneManager.OnSceneEvent -= SceneManager_OnSceneEvent;
 
             // Set the active scene to be the 1st scene loaded so we don't instantiate within the test runner scene.
-            SceneManager.SetActiveScene(m_ScenesLoaded[0]);
+            SetActiveScene(m_ScenesLoaded[0]);
 
             var autoSyncActive = new List<NetworkObject>();
             // Spawn 3 NetworkObject instances that auto synchronize to active scene changes
@@ -385,7 +391,8 @@ public IEnumerator ActiveSceneSynchronizationTest()
 
             // Now change the active scene
             var newActiveScene = m_ScenesLoaded[1];
-            SceneManager.SetActiveScene(newActiveScene);
+            SetActiveScene(newActiveScene);
+
             // We have to do this
             //Object.DontDestroyOnLoad(m_TestPrefabAutoSynchActiveScene);
 
@@ -451,11 +458,18 @@ public IEnumerator ActiveSceneSynchronizationTest()
 
             // Now unload the active scene to verify all remaining NetworkObjects are migrated into the SceneManager
             // assigned active scene
-
+            m_UnloadEventCompleted = false;
+            authority.SceneManager.OnUnloadEventCompleted += OnUnloadEventCompleted;
             authority.SceneManager.UnloadScene(newActiveScene);
-            yield return WaitForConditionOrTimeOut(log => ValidateSceneOnAllClients(log, sceneToMigrateTo.name, ExpectedLoadType.Unloaded));
+
+            // Always first: make sure the scene event has completed.
+            yield return WaitForConditionOrTimeOut(() => m_UnloadEventCompleted);
             AssertOnTimeout($"Timed out waiting for all clients to unload scene {newActiveScene.name}!");
 
+            // Always second: make sure all spawned objects are in the correct scene
+            yield return WaitForConditionOrTimeOut(log => ValidateSceneOnAllClients(log, sceneToMigrateTo.name, ExpectedLoadType.Unloaded));
+            AssertOnTimeout($"Timed out waiting for all clients to validate the correct scenes for spawned objects!");
+
             // Clean up any destroyed NetworkObjects
             for (int i = authoritySpawnedInstances.Count - 1; i >= 0; i--)
             {
@@ -482,6 +496,13 @@ public IEnumerator ActiveSceneSynchronizationTest()
             Assert.AreEqual(3, autoSyncInactive.Count(obj => obj != null), $"All the NetworkObjects with {nameof(NetworkObject.ActiveSceneSynchronization)}=false should have survived the active scene change!");
         }
 
+
+        private bool m_UnloadEventCompleted;
+        private void OnUnloadEventCompleted(string sceneName, LoadSceneMode loadSceneMode, List<ulong> clientsCompleted, List<ulong> clientsTimedOut)
+        {
+            m_UnloadEventCompleted = true;
+        }
+
         /// <summary>
         /// Callback invoked when a test prefab, with the <see cref="DestroyWithSceneInstancesTestHelper"/>
         /// component attached, is destroyed.