World/Udon Bugs & Feature Requests

Manual synchronization stops updating synced variables on non-owner clients with certain field configurations, despite the owner reporting successful serialization. In the failing cases, the non-owner receives OnDeserialization, but the synced fields remain at their initial values. ENVIRONMENT ──────────────────────── Unity: 2022.3.22f1 VRChat Worlds SDK: 3.10.4 Tested with actual VRChat clients in the same instance STEPS TO REPRODUCE ──────────────────────── Attach the provided Float20SyncProbe and Double20SyncProbe scripts to separate GameObjects. Assign a separate TMP text display to each script. Upload the world and join the same instance with two players. The owner assigns new values and calls RequestSerialization() every 10 seconds. Compare the owner's values with the non-owner's values on the displays and in the logs. Both scripts use Manual synchronization. Only the owner writes the synced fields. Neither script uses FieldChangeCallback or calls Networking.SetOwner. Despite their filenames, the attached scripts currently contain: Float20SyncProbe: 27 synced floats. Double20SyncProbe: 14 synced doubles and 1 synced int. EXPECTED RESULT ──────────────────────── The non-owner's synced fields should update to match the owner's serialized values. ACTUAL RESULT ──────────────────────── With the failing configurations, the non-owner's fields remain at their initial values. Reducing the number of synced fields restores normal synchronization. TEST RESULTS ──────────────────────── All configurations below were tested without FieldChangeCallback. 2 doubles : Worked 2 floats : Worked 13 doubles : Worked 26 floats : Worked 14 doubles : Worked 27 floats : Failed 14 doubles + 1 int : Failed 20 doubles : Failed Earlier tests also reproduced the issue with 20 doubles using FieldChangeCallback, while 20 floats worked. Removing FieldChangeCallback did not resolve the double20 failure. The results suggest that the amount or layout of synced data may be involved, but the exact cause is unknown. POSSIBLY RELATED REPORTS ──────────────────────── A single UdonSharpBehavior with VRC Enable Persistence cannot store more than 108 bytes of the same variable type https://feedback.vrchat.com/persistence/p/a-single-udonsharpbehavior-with-vrc-enable-persistence-cannot-store-more-than-10 PlayerObject Persistence Fails to Respect Sync Mode https://feedback.vrchat.com/persistence/p/playerobject-persistence-fails-to-respect-sync-mode Those reports concern Persistence restoration. This issue occurs during ordinary owner-to-non-owner synchronization within the same instance. REPRODUCTION MATERIALS ──────────────────────── The attached scripts reproduce the issue independently and display each client's local synced values, receive count, consistency check, and serialization result.

When loading into an existing group instance - there is a chance that VRC will crash right to desktop with no error code. You can easily repeat it with the same group instance but when you make your own instance, it works fine.

The normal UdonSharpBehaviour SendCustomNetworkEvent lacks the targeted overloadings of NetworkCalling.SendCustomNetworkEvent(IUdonEventReceiver, ...) . And NetworkCalling.SendCustomNetworkEvent() do not have the non-targeted overloadings. So they are not identical as the docs says. This is an incomplete implementation of a method that is supposed to be identical. Make them identical.

View the VRChat Home world photo: https://vrchat.com/home/world/wrld_4432ea9b-729c-46e3-8eaf-846aa0a37fdd/info Visit the world and look at the advertisement space next to the world mirror on the left, notice it's different. Expected result: The world picture should match the world, currently the Spookality 2026 Bundle. Actual result: An older world photo from Tanabata Bundle promo from July 3, 2026 to September 4, 2026 is shown on the world page. The yellow cube is missing from the world. Additional information: Since the Creator Guidelines was updated on October 6, 2026, this world may be in violation of the recent new guideline about misleading or deceptive thumbnails: > Content should accurately represent what a user will experience. Names, tags, descriptions, images, acknowledgements, and previews (including thumbnails) should not be misleading. If your content looks different in VRChat than in the images you've used to showcase it, users may have a negative experience. Notably, the banners are different and the Jimothy raccoon avatar may or may not be seen.

If you sync a vrcurl or an array, their respective variable Change events will activate every time there's a deserialization for non-owners. This will happen regardless of if sendChange is on or not, they will be considered Changed every time. The attached picture is an example graph: Even though the SyncedInt is the only variable being changed, the SyncedURL and SyncedIntArray Change events will also activate for non-owners.

Ownership can permanently desync between clients in an unexpected way The included script can generate such a desync, please assign a TMP text field to view it, then join with 2 clients --- Of note for anyone experiencing this, I've had some success mitigating it by overriding OnOwnershipRequest and returning true public override bool OnOwnershipRequest(VRCPlayerApi requestingPlayer, VRCPlayerApi requestedOwner) { return true; }

repro world: https://vrchat.com/home/world/wrld_685838b2-dc34-47c7-8adf-92d5016075dc repro procedure: Join two clients. Watch bandwidth (debug menu 4) usage on master. On live it's around 3 k/s, on danly-perf it's over 10 k/s (sometimes ending up with a persistent death run which degrades IK fidelity) Debug 8 will show BW 0.00b/s for tiles not moving on live, but around 40-80 on danly-perf Images are perf branch and (a slightly old) live branch screenshot of debug 4 and 8 showing the bandwidth usage difference.

Writing a U# program like so, will fail with: Method is not exposed to Udon: 'texture.SetPixelData(d, 0, 0)'. Even though it is exposed as UnityEngineTexture2D.__ctor__SystemInt32_SystemInt32_UnityEngineTextureFormat_SystemBoolean__UnityEngineTexture2D U# Code: var texture = new Texture2D( 2, 2, TextureFormat.RGBA32, false ); uint[] d = new uint[2 * 2 * 4]; texture.SetPixelData(d, 0, 0); However it will compile in udon graph, but the data input will be a Object[], and will crash with anything passed to it. Manually writing some udon assembly will compile again, but will also crash at runtime udon assembly: .data_start .export tex .export arr .export num0 .export num1 .export f .export tex_format tex: %UnityEngineTexture2D, null arr: %SystemSingleArray, null num0: %SystemInt32, null num1: %SystemInt32, null f: %SystemBoolean, null tex_format: %UnityEngineTextureFormat, null .data_end .code_start .export Test Test: PUSH, num1 PUSH, num1 PUSH, tex_format PUSH, f PUSH, tex EXTERN, "UnityEngineTexture2D.__ctor__SystemInt32_SystemInt32_UnityEngineTextureFormat_SystemBoolean__UnityEngineTexture2D" PUSH, tex PUSH, arr PUSH, num0 PUSH, num0 EXTERN, "UnityEngineTexture2D.__SetPixelData__TArray_SystemInt32_SystemInt32__SystemVoid" JUMP, 0xFFFFFFFC .code_end udon assembly crash: VRC.Udon.VM.UdonVMException: The VM encountered an error! Exception Message: An exception occurred during EXTERN to 'UnityEngineTexture2D.__SetPixelData__TArray_SystemInt32_SystemInt32__SystemVoid'. Parameter Addresses: 0x00000000, 0x00000001, 0x00000002, 0x00000002 Cannot retrieve heap variable of type 'Single[]' as type 'Object[]' ---------------------- Program Counter was at: 80 ---------------------- Stack Dump: ---------------------- Heap Dump: 0x00000000: (UnityEngine.Texture2D) 0x00000001: System.Single[] 0x00000002: 0 0x00000003: 1 0x00000004: False 0x00000005: RGBAFloat 0x00000006: UnityEngineTexture2D.__ctor__SystemInt32_SystemInt32_UnityEngineTextureFormat_SystemBoolean__UnityEngineTexture2D 0x00000007: UnityEngineTexture2D.__SetPixelData__TArray_SystemInt32_SystemInt32__SystemVoid ---------------------- Inner Exception: ---> VRC.Udon.VM.UdonVMException: An exception occurred during EXTERN to 'UnityEngineTexture2D.__SetPixelData__TArray_SystemInt32_SystemInt32__SystemVoid'.

SDK 3.10.5 See below code, it outputs "false, true, true" (and vice versa) which is obviously wrong. However if the property is public it outputs "true, true, true" as expected. using UdonSharp; using UnityEngine; [UdonBehaviourSyncMode(BehaviourSyncMode.None)] public class WhyPropertyNoWork : UdonSharpBehaviour { private int state; private const int TestState = 3; private bool IsTestState { get { return state == TestState; } set { } } private WhyPropertyNoWork _whyThis; private void Start() { state = TestState; _whyThis = this; } public override void Interact() { Debug.Log( $"TESTTEST, _whyThis.IsTestState={_whyThis.IsTestState}, IsTestState={IsTestState}, _whyThis.IsTestState={_whyThis.IsTestState}"); if (state == 3) state = 0; else state = TestState; } }

If a person were to go into a Station that has disableStationExit enabled, then you set disableStationExit to false, the player in that chair does not get the update and are unable to leave the chair, same in reverse. As well, calling ExitStation on that chair while disableStationExit is true does nothing, which would be my only way around the previous issue.