NetworkManager shutdown maintains references for the next scene

[ArthurTelles]

Description

After entering a scene and spawning NetworkObjects, I shutdown the NetworkManager and go back to the lobby. However, when transitioning to another scene and starting as a host again the NetworkManager starts showing errors from references from the previous scene.

Reproduce Steps

1. Start the project in Scene A with NetworkManager not started

2. In Scene B, start the host and spawn NetworkObjects that are nested

3. Shut down the NetworkManager and return to Scene A

4. Move back to Scene B, start as a host again, and encounter continuous error logs.

Actual Outcome

After exiting and entering the same scene the NetworkManager appears to maintain references from older NetworkObjects making the project throw uncountable errors.

Expected Outcome

The exact same code works fine on the NGO 1.12.2 but keeps throwing those errors on the versions 2+.

Environment

• OS: macOS 15.2
• Unity Version: 6000.0.34f1
• Netcode Version: 2+

Additional Context

Here's is the error log I keep receiving after updating the version:

MissingReferenceException: The object of type 'Unity.Netcode.NetworkObject' has been destroyed but you are still trying to access it.
Your script should either check if it is null or you should not destroy the object.
UnityEngine.Object+MarshalledUnityObject.TryThrowEditorNullExceptionObject (UnityEngine.Object unityObj, System.String parameterName) (at /Users/bokken/build/output/unity/unity/Runtime/Export/Scripting/UnityEngineObject.bindings.cs:869)
UnityEngine.Bindings.ThrowHelper.ThrowNullReferenceException (System.Object obj) (at /Users/bokken/build/output/unity/unity/Runtime/Export/Scripting/BindingsHelpers.cs:61)
UnityEngine.Component.get_gameObject () (at <eac12af5e0034b02b1bfe348a7feb8c6>:0)
Unity.Netcode.NetworkObject.UpdateForSceneChanges () (at ./Library/PackageCache/com.unity.netcode.gameobjects/Runtime/Core/NetworkObject.cs:3318)
Unity.Netcode.NetworkObject.UpdateNetworkObjectSceneChanges () (at ./Library/PackageCache/com.unity.netcode.gameobjects/Runtime/Core/NetworkObject.cs:3287)
Unity.Netcode.NetworkManager.NetworkUpdate (Unity.Netcode.NetworkUpdateStage updateStage) (at ./Library/PackageCache/com.unity.netcode.gameobjects/Runtime/Core/NetworkManager.cs:404)
Unity.Netcode.NetworkUpdateLoop.RunNetworkUpdateStage (Unity.Netcode.NetworkUpdateStage updateStage) (at ./Library/PackageCache/com.unity.netcode.gameobjects/Runtime/Core/NetworkUpdateLoop.cs:191)
Unity.Netcode.NetworkUpdateLoop+NetworkPostLateUpdate+<>c.<CreateLoopSystem>b__0_0 () (at ./Library/PackageCache/com.unity.netcode.gameobjects/Runtime/Core/NetworkUpdateLoop.cs:286)

[NoelStephensUnity]

This is a verified issue under the conditions outlined above.
The resolution to the issue is to clear out the NetworkObject.NetworkObjectsToSynchronizeSceneChanges upon shutting down the NetworkManager.

This only impacts v2.x.

[ArthurTelles]

This is a verified issue under the conditions outlined above. The resolution to the issue is to clear out the NetworkObject.NetworkObjectsToSynchronizeSceneChanges upon shutting down the NetworkManager.

This only impacts v2.x.

Hey @NoelStephensUnity! I couldn’t find this NetworkObject property—just wondering, is it public? Or is there something I could do manually to clear this?

[NoelStephensUnity]

This is a verified issue under the conditions outlined above. The resolution to the issue is to clear out the NetworkObject.NetworkObjectsToSynchronizeSceneChanges upon shutting down the NetworkManager.
This only impacts v2.x.

Hey @NoelStephensUnity! I couldn’t find this NetworkObject property—just wondering, is it public? Or is there something I could do manually to clear this?

Apologies, those were notes to any team member that might pick up this issue before I have a chance to circle back around to it.

It is an issue that we need to resolve.

[NoelStephensUnity]

#3230 has been merged and this issue will be resolved in the next v2.2.x NGO update.
Closing the issue at this time, but feel free to re-opening it if upon installing the next package update the problem persists.