World/Udon Bugs & Feature Requests

If you attempt to create an array of UdonBehaviours by naming the type VRCUdonUdonBehaviourArray, it does not get recognized as a valid Udon type and fails to assemble. The alternate special case type "VRCUdonCommonInterfacesIUdonEventReceiver" that's used in other places that takes the place of UdonBehavior doesn't have an array type of "VRCUdonCommonInterfacesIUdonEventReceiverArray" defined either. So at the moment we need to use arrays of Component to represent arrays of UdonBehaviours. This issue is probably related and seems like a workaround on the graph side or a bug that's hiding the issue: https://vrchat.canny.io/vrchat-udon-closed-alpha-bugs/p/udonbehaviour-variable-compiles-into-unityengineobjectarray-which-is-an-object

VRCSDK 3.7.5 Steps to Reproduce: Attach the VRC Enable Persistence component and VRC Player Object component to an object. Attach the following UdonSharp script to the same object. Execute Interact() in ClientSim. --- using UdonSharp; using UnityEngine; using VRC.SDKBase; using VRC.Udon; [UdonBehaviourSyncMode(BehaviourSyncMode.Manual)] public class VRCURLPersistenceTest : UdonSharpBehaviour { [UdonSynced] private VRCUrl testUrl; public override void Interact() { RequestSerialization(); } } --- Observed Error: When running the script in ClientSim, the following NullReferenceException occurs: --- NullReferenceException: Object reference not set to an instance of an object VRC.SDK3.ClientSim.Editor.VisualElements.Fields.FieldFactory.GenerateField[T] (System.String fieldName, T data) (at ./Packages/com.vrchat.worlds/Integrations/ClientSim/Editor/VisualElements/Fields/FieldFactory.cs:79) VRC.SDK3.ClientSim.Editor.VisualElements.EncodeDecodeEditors.ClientSimUdonEncodeDecodeEditor.GenerateFields (UnityEngine.MonoBehaviour component, VRC.SDK3.Data .DataDictionary data) (at ./Packages/com.vrchat.worlds/Integrations/ClientSim/Editor/VisualElements/EncodeDecodeEditors/ClientSimUdonEncodeDecodeEditor.cs:30) VRC.SDK3.ClientSim.Editor.VisualElements.ClientSimNetworkHolderInstanceElement.GenerateDataElements (System.Int32 index) (at ./Packages/com.vrchat.worlds/Integrations/ClientSim/Editor/VisualElements/ClientSimNetworkHolderInstanceElement.cs:72) VRC.SDK3.ClientSim.Editor.VisualElements.ClientSimNetworkHolderInstanceElement.UpdateData (VRC.SDK3.ClientSim.Editor.ClientSimPlayerObjectWindow+PlayerObjectData data) (at ./Packages/com.vrchat.worlds/Integrations/ClientSim/Editor/VisualElements/ClientSimNetworkHolderInstanceElement.cs:94) VRC.SDK3.ClientSim.Editor.ClientSimPlayerObjectWindow.UpdateCurrentPage (VRC.SDK3.ClientSim.ClientSimOnPlayerObjectUpdateEndedEvent e) (at ./Packages/com.vrchat.worlds/Integrations/ClientSim/Editor/Windows/ClientSimPlayerObjectWindow.cs:259) VRC.SDK3.ClientSim.ClientSimEventDispatcher.SendEvent[T] (T clientSimEvent) (at ./Packages/com.vrchat.worlds/Integrations/ClientSim/Runtime/Events/ClientSimEventDispatcher.cs:62) VRC.SDK3.ClientSim.Persistence.ClientSimPlayerObjectStorage.LateUpdate () (at ./Packages/com.vrchat.worlds/Integrations/ClientSim/Runtime/Player/PlayerPersistence/ClientSimPlayerObjectStorage.cs:172) --- Workaround: Setting an initial value for the synced VRCUrl variable prevents the error: --- [UdonSynced] private VRCUrl testUrl = VRCUrl.Empty; --- Possible Cause & Suggestion: It seems that ClientSim does not handle null values properly when processing synced variables. Adding proper null handling for synced variables, especially for VRCUrl, may help prevent this error.

Environment: Unity version: 2022.3.22f1 VRChat SDK Worlds: 3.10.3 VRChat SDK Base: 3.10.3 UdonSharp included with SDK Project uses Prefab Mode / PrefabStage with UdonSharpBehaviour components YamaPlayer package present: net.kwxxx.yama-stream 1.5.18 Observed: When opening or editing prefabs containing UdonSharpBehaviour components in Prefab Mode, Unity logs repeated ArgumentNullException errors from OdinSerializer UnitySerializationUtility. Error: ArgumentNullException: Value cannot be null. Parameter name: unityObject VRC.Udon.Serialization.OdinSerializer.UnitySerializationUtility.SerializeUnityObject(...) UdonSharp.UdonSharpBehaviour.UnityEngine.ISerializationCallbackReceiver.OnBeforeSerialize() and similarly: UnitySerializationUtility.DeserializeUnityObject(...) UdonSharp.UdonSharpBehaviour.UnityEngine.ISerializationCallbackReceiver.OnAfterDeserialize() Trigger: Open a prefab containing UdonSharpBehaviour in Prefab Mode Move a child object or let PrefabStage autosave run Errors repeat, sometimes dozens/hundreds per save Expected: PrefabStage autosave should not throw if a Unity pseudo-null UdonSharpBehaviour or serialized target is encountered. It should skip invalid objects or handle UnityEngine.Object pseudo-null safely. Additional finding: For diagnosis only, I temporarily tested a local guard around the SDK serialization path. The test indicated that the affected object was not a normal C# null reference, but behaved as null through Unity's overloaded UnityEngine.Object null comparison. With that guard in place, the exception stopped. I am not using this as a permanent workaround and do not intend to publish content with a modified SDK. This observation is included only to help identify the likely failure path. Additional observation: I have encountered this issue twice. In both cases, once the issue started occurring in the project, checking out older repository commits did not reliably make the issue disappear. This suggests that the trigger may involve Unity Library/cache/generated SDK state or some project-local serialized state, not only the currently checked out asset files.

If an object with an object sync component is inactive and a user enters the world late and interacts with it (in our case, "activates" it), it will sync in the wrong place: A location that was previously 'deactivated'. Other objects that were not interacted with in that world will work fine, and users who entered the world earlier will work fine. But users who entered late will be screwed. Here's how we encountered the problem a user who has already entered the world grabs the object (owner set) the object is 'disabled'. someone enters the world late. there is a synchronization problem when the object is 'activated'. (*Honestly, this(4) is the hardest part to understand. It's hard for me to figure out if it's only a problem when it's activated, or if it's other things like transforms after it's activated.) *ex) transform, objectpool, teleport to

Log the bool "value" argument for InputUse. Click your mouse and release. Expected: receive "True" once, receive "False" once Actual:

Modulo against 2 long values is not correctly whitelisted. This is borked in all cases except with 2 constants inline, in which case C# just optimizes this away before it hits U#. Untested if other methods are also unavailable. Sample code: long a = 10L; long b = 20L; long c = a % b; Result: Method is not exposed to Udon: 'a % b' SDK: Worlds 3.7.2 Unity: 2022.3.22f1

As the title says. This is a variant that works with doubles instead of floats. SDK versions: SDK: Worlds 3.7.2 Unity: 2022.3.22f1

% operator (Remainder operator) is not exposed to Udon. This makes some operations impossible! I can't believe that this has been neglected since 2020. (I know https://feedback.vrchat.com/udon/p/long-remainder but it has been neglected since 2020 so I created new issue.)

I noticed VRCObjectSync.Respawn() can cause NullReferenceException and halts the udon, if its GameObject is inactive and never activated once. It seems caused by not having it's respawn information, which seems declared at its Start() . ( VRCObjectSync.Respawn() will send the object to the first position the object activated. Moving inactivated object will affect its respawn position.) There is no way to avoid its exception safely. We need to check to use if the object is active, but it means inactive object should not use Respawn() .