NetworkManager.OnServerStopped is called after NetworkManager.CustomMessagingManager is null

[HenryJones14]

NetworkManager.OnServerStopped is called after NetworkManager.CustomMessagingManager is null. This means that you cant cleanup (unsubscribe) events properly. This is not strictly needed because it will be set to null anyways, but it is better for consistency.

From what I can see the backend cant really call NetworkManager.OnServerStopped before null, so maybe there should be another event for managing events?

[HenryJones14]

Note: NetworkManager.NetworkTickSystem works great (nulled after NetworkManager.OnServerStopped)!

[NoelStephensUnity]

@HenryJones14
So, you are thinking about something like a NetworkManager.OnShutdownStarted event that is invoked prior to running through the shutdown sequence would be useful?

[HenryJones14]

@NoelStephensUnity
Not necessarily for shutdown, but for server stop. It is not for cleanup after networking shutdown, but rather when the server (or host) disconnects.

I am using a completely static approach for handling my game state (not a singleton), and I don’t really want to make the networking work in a different way. So far, it works perfectly besides this one bug. The fix is technically to just remove the line, but I feel like it should be fixed on the NGO side.

I will send a simplified code snippet after this.

[HenryJones14]

Error line:

// Causes error at ./Packages/com.unity.netcode.gameobjects/Runtime/Core/NetworkManager.cs:1648
NetworkManager.Singleton.CustomMessagingManager.OnUnnamedMessage -= UnnamedMessage;

Full code:

using UnityEngine;
using Unity.Netcode;

namespace DungeonMaster.CoreGame
{
    public static class NetcodeManager
    {
        [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.AfterAssembliesLoaded)]
        private static void RuntimeInitializeOnLoad()
        {
            Debug.Log("RuntimeInitializeOnLoad");
            NetworkManager.OnInstantiated += OnNetworkInstantiated;
            NetworkManager.OnDestroying += OnNetworkDestroying;
        }

        private static void OnNetworkInstantiated(NetworkManager NetworkManagerInstance)
        {
            Debug.Log("OnNetworkInstantiated");

            NetworkManagerInstance.OnServerStarted += OnNetworkServerStarted;
            NetworkManagerInstance.OnServerStopped += OnNetworkServerStopped;

            NetworkManagerInstance.OnClientStarted += OnNetworkClientStarted;
            NetworkManagerInstance.OnClientStopped += OnNetworkClientStopped;
        }

        private static void OnNetworkDestroying(NetworkManager NetworkManagerInstance)
        {
            Debug.Log("OnNetworkDestroying");

            NetworkManagerInstance.OnServerStarted -= OnNetworkServerStarted;
            NetworkManagerInstance.OnServerStopped -= OnNetworkServerStopped;

            NetworkManagerInstance.OnClientStarted -= OnNetworkClientStarted;
            NetworkManagerInstance.OnClientStopped -= OnNetworkClientStopped;
        }

        private static void OnNetworkServerStarted()
        {
            Debug.Log("OnNetworkServerStarted");

            NetworkManager.Singleton.NetworkTickSystem.Tick += OnNetworkTick;
        }

        private static void OnNetworkClientStarted()
        {
            Debug.Log("OnNetworkClientStarted");

            NetworkManager.Singleton.CustomMessagingManager.OnUnnamedMessage += UnnamedMessage;
        }

        private static void OnNetworkClientStopped(bool IsHost)
        {
            Debug.Log("OnNetworkClientStopped");

            NetworkManager.Singleton.CustomMessagingManager.OnUnnamedMessage -= UnnamedMessage; // FIXME Causes error at ./Packages/com.unity.netcode.gameobjects/Runtime/Core/NetworkManager.cs:1648
        }

        private static void OnNetworkServerStopped(bool IsHost)
        {
            Debug.Log("OnNetworkServerStopped");

            NetworkManager.Singleton.NetworkTickSystem.Tick -= OnNetworkTick;
        }

        private static void UnnamedMessage(ulong ClientID, FastBufferReader reader)
        {
            reader.ReadValueSafe(out string Message);

            if (ClientID == NetworkManager.ServerClientId) // sent from server
            {
                Debug.Log("Message recived from Server: " + Message);
            }
            else // sent from client
            {
                if (NetworkManager.Singleton.IsServer)
                {
                    Debug.Log("Message recived from Client: " + Message);
                }
                else
                {
                    Debug.Log("Message ignored: " + Message);
                }
            }
        }

        private static void OnNetworkTick()
        {
            Debug.Log("OnNetworkTick");
        }
    }
}

[NoelStephensUnity]

@HenryJones14 ,
Adjustments have been made to NetworkManager that will provide you with a NetworkManager.OnPreShutdown event that is invoked just prior to the NetworkManager running through the shutdown code. This should provide you with the ability to remove registrations with the NetworkManager.CustomMessagingManager prior to it becoming null.

Closing this issue as it was resolved in #3358 (v1.x) and #3366 (v2.x). This will be in the next NGO updates.
If you have further questions or feel this does not address your issue, please feel free to re-open this issue and provide us with further details.