SyncVar OnChange event not firing twice for Client and Server

[shelbyjuno]

General Unity version: 6000.0.18f1 Fish-Networking version: 4.4.5R (does NOT repro on 4.4.4R) Discord link 1: https://discord.com/channels/424284635074134018/1034477094731784302/1284362548635893760 Discord link 2: https://discord.com/channels/424284635074134018/1034477094731784302/1284577274552647795

Description When subscribing to the OnChange event on a SyncVar, only one event (where asServer == true) is fired when acting as both server and client.

Replication Steps to reproduce the behavior:

1. Import OnChangeBug.zip
2. Open scene, set the Player Prefab on the PlayerSpawner to the provided Player prefab if not already assigned
3. Start server and client
4. Press O and P to fire SyncVar changes and note debug logs
5. Notice that asServer only fires once.

Alternatively, create a new project and use a script such as:

public class Player : NetworkBehaviour
{
    readonly SyncVar<int> health = new SyncVar<int>(100);
    [ServerRpc] void RpcUpdateHealth(int newHealth) => health.Value = newHealth;

    private void Awake()
    {
        health.OnChange += OnHealthChange;
    }

    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.O)) RpcUpdateHealth(health.Value - 10);
        if (Input.GetKeyDown(KeyCode.P)) RpcUpdateHealth(health.Value + 10);
    }

    private void OnHealthChange(int prev, int next, bool asServer)
    {
        Debug.Log($"Health changed from {prev} to {next}. ({asServer})");
    }
}

Expected behavior When Server and Client, OnChange should fire two events, one with asServer == true and one asServer == false

Screenshots

4.4.5

4.4.4

[FirstGearGames]

I deleted the zip, it was too large of a project to investigate. Please check out these guidelines here and upload another if you could https://fish-networking.gitbook.io/docs/manual/guides/creating-bug-reports#guidelines

[shelbyjuno]

I deleted the zip, it was too large of a project to investigate. Please check out these guidelines here and upload another if you could https://fish-networking.gitbook.io/docs/manual/guides/creating-bug-reports#guidelines

My bad! I've updated the link with a small .unitypackage! OnChangeBug.zip

[maxkratt]

@shelbyjuno I just tried the example you made, and it's working correctly on my end. Here's a video showing it: https://github.com/user-attachments/assets/708a1996-ffde-4478-88ce-478547c63059

[maxkratt]

My most likely guess is your client isn't observing the object. Did you try rebuilding the scene ids from the Tools->FishNetworking toolbar menu?

[shelbyjuno]

@maxkratt That is extremely odd, I've recorded a video of me first trying 4.4.4 and then 4.4.5, while rebuilding scene IDs both times just to make sure there is nothing stupid I am missing:

https://github.com/user-attachments/assets/86c030a8-2f3f-4f12-8b88-d7f7c7847b3a

[FirstGearGames]

Most likely something in your project. Weird neither max nor myself could replicate the issue in the test files you provided though.

Setting this as 'waiting for information' until you find out something new. At this time we won't be able to look into it further until a project with the issue present is available to us.

[shelbyjuno]

No longer repros for me in 4.4.6R ! Thanks guys.