MultiplayerSynchronizer - "Watch" properties - on_delta_receive: Condition "props.size() == 0" is true. Returning: ERR_INVALID_DATA

[Federick732000]

Godot version

v4.1.beta2.mono.official [a2575cba4]

System information

Godot v4.1.beta2.mono - Windows 10.0.19045 - Vulkan (Forward+) - dedicated GeForce RTX 2060 () - AMD Ryzen 5 2600X Six-Core Processor (12 Threads)

Issue description

I'm using a Multiplayer Synchronizer to sync some variables of two instantiated players (each one has local multiplayer authority). Setting the "watch" property on the multiplayer synchronizer properties causes the player who receive the delta update to receive this error and to not store the updated value:

E 0:00:01:0604   on_delta_receive: Condition "props.size() == 0" is true. Returning: ERR_INVALID_DATA
  <C++ Source>   modules/multiplayer/scene_replication_interface.cpp:778 @ on_delta_receive()

I don't know if the problem is Mono-specific, but the error comes up even on Node3D default properties.

Steps to reproduce

• Create a simple scene with a platform
• Create a "Player" scene, that contains a MultiplayerSynchronizer, and put some properties to sync with the "watch" property ON and the "sync" property to OFF
• Create a script to make one player create the server and the other to connect as a client to the server
• Make the server instantiate the player on connect
• Make a script to change the synced variables, to trigger the watched properties change

Minimal reproduction project

Test_delta.zip Test_delta-gdscript.zip

[AThousandShips]

Please test if this is specific to C# and if not add an MRP that has GDScript as well:

• Note for C# users: If your issue is not Mono-specific, please upload a minimal reproduction project written in GDScript or VisualScript. This will make it easier for contributors to reproduce the issue locally as not everyone has a Mono setup available.

This will greatly speed up any resolution to this because most bug testers here don't use Mono (like me), and even if we were to be able to convert the code to GDScript by looking at the code it wouldn't be certain it's actually replicating the same behaviour

It also helps to pin down what's actually wrong

[Federick732000]

Understood. I converted the project to gdscript and the problem is still there. I added the project to the issue

[AThousandShips]

Thank you!