Uninitialized network variable

[Wolframwow]

Description of bug:

I am trying to have a global component (network object) in the scene which acts as a "Tick generator" so that all players generate resources simultaneously. This component should invoke an event which is triggered by changing a network variable (already declared with value 0) , by the Server (NetworkManager). This component's prefab is also registered inside the NetworkPrefabs section of the NetworkManager.
Warning caught when starting server:

"NetworkVariable is written to, but doesn't know its NetworkBehaviour yet. Are you modifying a NetworkVariable before the NetworkObject is spawned?"

Even if the network variable changed, this won't get replicated to the clients.
It has both network object and network behaviour and it is spawned.

Reproducible?

Yes, in 50% of the cases. Sometimes the component works as intended.

Steps to reproduce:

• attach following script to a component in the scene (see below, at the end)
• the network manager should find this component in the scene and when the server starts, it should change the network variable within this component (increment), via a public method
• start server

Outcome:
in 50% of the cases the warning appears, even if the The steps above should be repeated several times because it might not occur on the 1st try

Expected behavior:
In the 50% of the working cases, there is no warning, and the network variable (from within this component) is getting replicated to the clients, which then get notified via this event.

Additional Remarks:
The issue does NOT occur at all if it is spawned dynamically!
As discussed on the discord channel, this might offer a better insight

Environment used:

• Win 11
• Unity Editor Version: 2022.2.15f1
• UnityNetcode for GameObjects Version: 1.2.0
• Unity Transport Version: 1.3.3

Network Manager setup:

Component code used:
Description of bug:

I am trying to have a global component (network object) in the scene which acts as a "Tick generator" so that all players generate resources simultaneously. This component should invoke an event which is triggered by changing a network variable (already declared with value 0) , by the Server (NetworkManager). This component's prefab is also registered inside the NetworkPrefabs section of the NetworkManager.
Warning caught when starting server:

"NetworkVariable is written to, but doesn't know its NetworkBehaviour yet. Are you modifying a NetworkVariable before the NetworkObject is spawned?"

Even if the network variable changed, this won't get replicated to the clients.
It has both network object and network behaviour and it is spawned.

Reproducible?

Yes, in 50% of the cases. Sometimes the component works as intended.

Steps to reproduce:

• attach following script to a component in the scene (see below, at the end)
• the network manager should find this component in the scene and when the server starts, it should change the network variable within this component (increment), via a public method
• start server

Outcome:
in 50% of the cases the warning appears, even if the The steps above should be repeated several times because it might not occur on the 1st try

Expected behavior:
In the 50% of the working cases, there is no warning, and the network variable (from within this component) is getting replicated to the clients, which then get notified via this event.

Additional Remarks:
The issue does NOT occur at all if it is spawned dynamically!
As discussed on the discord channel, this might offer a better insight

Environment used:

• Win 11
• Unity Editor Version: 2022.2.15f1
• UnityNetcode for GameObjects Version: 1.2.0
• Unity Transport Version: 1.3.3

Network Manager setup:

Component code used:

public class D_TickHandler : NetworkBehaviour
{
    /// <summary>
    /// int: old tick value. int: new tick value
    /// </summary>
    public event Action<int, int> tickgenerated;
    [SerializeField] public static D_TickHandler singleton = null;
    [SerializeField] NetworkVariable<int> tickGenerated = new NetworkVariable<int>(0);
    public D_TickHandler()
    {
        if (singleton == null)
        {
            singleton = this;
        }
    }
    private void Awake()
    {
        tickGenerated.OnValueChanged += HandleValueChanged;
        DontDestroyOnLoad(this);
    }
    private void OnApplicationQuit()
    {
        tickGenerated.OnValueChanged -= HandleValueChanged;
    }
    public override void OnNetworkSpawn()
    {
        Debug.Log("D_TickHandler. OnNetworkSpawn");
        StartCoroutine(UpdateTick(2));
    }
    private void HandleValueChanged(int previousValue, int newValue)
    {
        Debug.Log("HandleValueChanged. invokeTickEvent called");
        tickgenerated?.Invoke(previousValue, newValue);
    }
    /// <summary>
    /// This can be called by the server periodically to trigger a tick across server or within ServerRPC
    /// </summary>
    public void invokeTickValueChange()
    {
        if (!IsServer) { return; }
        Debug.Log("invokeTickValueChange");
        tickGenerated.Value += 1;
    }
    IEnumerator UpdateTick(float waitTime)
    {
        if(!IsServer) { yield return null; }
        while (true)
        {
            yield return new WaitForSeconds(waitTime);
            invokeTickValueChange();
        }
    }
}

[PitouGames]

I always read that using constructor in MonoBehaviour (and derived class like NetworkBehaviour) is not recommended and should be avoided. Maybe it plays a role in this issue?

[NoelStephensUnity]

@Wolframwow

Are you still having issues with this?
If so, you might try something like this:

public class D_TickHandler : NetworkBehaviour
{
    public static D_TickHandler singleton = null;
    /// <summary>
    /// int: old tick value. int: new tick value
    /// </summary>
    public UnityEvent<int, int> Tickgenerated;
    public float TickRate = 2.0f;
    private NetworkVariable<int> m_TickGenerated = new NetworkVariable<int>(0);
    
    private float m_NextTickUpdate;

    private void Awake()
    {
        if (singleton == null)
        {
            singleton = this;
        }
        DontDestroyOnLoad(this);
    }

    protected override void OnNetworkPostSpawn()
    {
        Debug.Log("D_TickHandler. OnNetworkSpawn");
        m_TickGenerated.OnValueChanged += TickChanged;
        if (IsServer)
        {
            NetworkManager.NetworkTickSystem.Tick += OnNetworkTick;
            m_NextTickUpdate = Time.realtimeSinceStartup + TickRate;
        }
        else
        {
            // Denotes beginning of tick synchronization
            TickChanged(m_TickGenerated.Value, m_TickGenerated.Value);
        }
        base.OnNetworkPostSpawn();
    }

    public override void OnNetworkDespawn()
    {
        m_TickGenerated.OnValueChanged -= TickChanged;
        NetworkManager.NetworkTickSystem.Tick -= OnNetworkTick;
        base.OnNetworkDespawn();
    }

    private void TickChanged(int previousTick, int currentTick)
    {
        Debug.Log($"[TickChanged] Prev = {previousTick} | {currentTick}");
        Tickgenerated?.Invoke(previousTick, currentTick);
    }

    private void OnNetworkTick()
    {
        if (m_NextTickUpdate <= Time.realtimeSinceStartup)
        {
            IncrementTickValue();
        }
    }

    /// <summary>
    /// This can be called by the server periodically to trigger a tick across server or within ServerRPC
    /// </summary>
    public void IncrementTickValue()
    {
        if (!IsServer) { return; }
        Debug.Log("IncrementTickValue");
        m_TickGenerated.Value += 1;
        m_NextTickUpdate = Time.realtimeSinceStartup + TickRate;
    }
}