World/Udon Bugs & Feature Requests

Gravity and Kinematic flags on VRCObjectSync components don't sync correctly right now and also cannot be set correctly while holding the pickup. To set gravity or kinematic flags, VRChat added two new methods for us: https://udonsharp.docs.vrchat.com/vrchat-api/#vrcobjectsync (they are supposed to behave like a synced variable) There are two bugs related to this: ~ Bug 1: ~ All you need is to create a pickup that has no gravity and then toggle the gravity flag on the VRCObjectSync component with an external button after claiming ownership. Then you let different people in the world pick up the pickup and drop it (to show their own local state). In my tests, this resulted in a pickup where the gravity flag is wildly different on each client and only syncs occasionally or not at all. They would see the pickup drop on my end, but when they pick it up it has no gravity for them. ~ Bug 2: ~ All you need is to create a pickup that has no gravity and then toggle the gravity flag on the VRCObjectSync component in OnPickupUseDown() . In my tests, this resulted in a pickup where the gravity stays enabled after the first OnPickupUseDown() and I am unable to turn gravity off again. To check gravity, the pickup is dropped. You can also just test it out here: Right setup: Bug 1 / Left setup: Bug 2 https://vrchat.com/home/world/wrld_9cefd5ec-4492-43c5-8cd3-05036c494556 Additional note: Since we only got a setter and not a getter method, we are left in the dark here when it comes to analyzing the problem. Reading out the local rigidbody state doesn't give us access to the real synced state. A getter method should be added.

Events like: InputUse InputJump InputMoveHorizontal InputMoveVertical InputLookHorizontal InputLookVertical Are still called even if the GameObject is disabled with SetActive(false) (See screenshots). But disabling the script with enabled = false; works. I am not sure if this is an expected behavior, but personally that issue confused me, If I disable a GameObect I would expect everything to be disabled, not just certain events like Update(), FixedUpdate(), OnDeserialization()...

When adding [UdonBehaviourSyncMode(BehaviourSyncMode.NoVariableSync)] to an udon# class, It will just continue using the last setting. For example if you add [UdonBehaviourSyncMode(BehaviourSyncMode.Continuous)] and then compile, then change it to [UdonBehaviourSyncMode(BehaviourSyncMode.NoVariableSync)] and compile again, you get the expected behavior, and calling SendCustomNetworkEvent() works. If you then change it to [UdonBehaviourSyncMode(BehaviourSyncMode.None)] and compile, then change it to [UdonBehaviourSyncMode(BehaviourSyncMode.NoVariableSync)] and compile again It will continue to behave exactly as if it's still set to None. SendCustomNetworkEvent() does not work. This is on an object that doesn't have any other scripts on it. I haven't tested the case with other scripts. You can look at the debug inspector to confirm that this is what is happening. From the documentation: "NoVariableSync: Enforces that there are no synced variables on the behaviour, hides the sync mode selection dropdown, and allows you to use the behaviours on GameObjects that use either Manual or Continuous sync." It seems like the case where a script using NoVariableSync being used on an object that doesn't have another script on it may have been overlooked. Since I'm updating a script in a prefab I'm releasing from None to NoVariableSync because I want to use network events now, it's not going to work for anyone updating to the new version. I am forced to set it to Continuous. Does anyone know if it makes any difference to bandwidth usage?

This has been broken for a long while, since I can remember, Auto Hold does not work for Oculus, or Index, but does work for Desktop, and (last I checked) Vive.

This was reported as fixed in 2024.4.1p3 but it looks like the problem crept back in and exists in SDK 3.8.2 / 2025.3.1 (haven't tested any other versions). Since the previous canny was closed out as complete, thought I'd open a new one. Prior bug report on this issue: https://feedback.vrchat.com/udon/p/braces-inside-strings-in-vrcjson-can-fail-to-deserialize // This works if(VRCJson.TryDeserializeFromJson("\"{\"data\":\"test\"}", out DataToken token2)) Debug.LogError("Failed to deserialize JSON"); else Debug.Log("Successfully deserialized JSON"); // This fails. Only difference is the braces after the word test in the JSON string. Number of braces or their configuration doesn't seem to make a difference. if(VRCJson.TryDeserializeFromJson("{\"data\":\"test{}\"}", out DataToken token1)) Debug.LogError("Failed to deserialize JSON"); else Debug.Log("Successfully deserialized JSON"); Thanks! -Tea

Since the avatar scaling update, I've been having problems with stations, and using the events for them. One thing I've nailed down, is that players are kicked from a station for a bit when they change avatar ( https://youtube.com/shorts/JHKDN4W7edE?feature=share ), and this causes the events 'onStationEnter' and 'onStationExited' to play; which messes up any logic that resets the station on leave. To fix this, I've had to add delay to the stations logic in my 'go kart zombie tag' world, but it's far from perfect, and would be really hard for a newcomer to udon. Also, the 'onStationExited' event gets called for both local and global players, which means the delayed enter and exit is unpredictable, as it is just whenever they see them load in. This can be seen in this clip, though there was a patch a couple of days later that fixed the event being called for the loading avatar as well ( https://youtu.be/1iNC3906fn8 ). For the record, this is a showcase of the avatar loading problem that has seems to be fixed now, where the kart would respawn, but then snap back to the sync script's location; as the player didn't actually leave the kart ( https://youtube.com/shorts/kX_9dtadUCc?feature=share ) Other than that, Something I can't fix is that I'm also having massive desyncing problems between quest and pc users; where sometimes pc users don't see a quest user enter a kart, and vice versa. This is leading to broken logic of non tag-able karts, and cases of two people in the same kart; with one driving (sorry, I don't have a video to show this)

On the documentation page for Input Events ( https://creators.vrchat.com/worlds/udon/input-events/ ) "InputDrop" is said to be true for releasing the grip buttons on controllers other than vive wands or some WMR controllers. I've been doing a few tests with the input mappings to see how they behave between players using Vive wands and other controller types. So far, I've found that the "release grip" condition for InputDrop becoming true is only the case (for a single frame, which is good) when using Hand Tracking on Quest standalone, but I was unable to trigger it from releasing grip any other way. Oculus controllers - both from PCVR through SteamVR via Virtual Desktop, and on the standalone version - from my testing cannot fire InputDrop at all. Index controllers also can't fire it all either. I feel as though either this needs to be changed in the client or the documentation needs to be updated... With this in mind though, currently a usable workaround is to just do the "release grip" check on our own via Udon, using the InputGrab event and checking for False. P.S: I also found that the OnInputMethodChanged event always says SteamVR2 when playing from PCVR, regardless of the actual input type, but this was already reported in another post. Also, The input method for Hand Tracking on Android returns a value of 19, which is not documented as the highest value shown on the website is 18. My IDE says that it does exist however with an enum called "VRCInputMethod.Count" instead of using "VRCInputMethod.QuestHands"? Still strange.

Both of these solutions always return false, a friend tested using HTC Vive + Vive Wands bool viveWorkaround; public override void InputDrop(bool isTrue, UdonInputEventArgs args) { Debug.Log(viveWorkaround); } Attempt 1: void Start() { viveWorkaround = InputManager.GetLastUsedInputMethod() == VRCInputMethod.Vive; } Attempt 2: public override void OnInputMethodChanged(VRCInputMethod inputMethod) { viveWorkaround = inputMethod == VRCInputMethod.Vive; }

Repro: var bounds = new Bounds( Vector3.zero , Vector3.one ); Debug.Log("Bounds: " + bounds.size); bounds.Expand(100f); Debug.Log("Bounds: " + bounds.size);

It works fine on UnityEditor, but when I build to VRChat's OfflineTest, I get an error that the TextMeshProUGUI attached to the Instantiated GameObject is null. Does the SerializeField get stripped when Instantiated for VRChat use? I would like to know if you know how to solve this problem. [UdonSharp][Unknown] Assets/**/Scripts/Presentation/**.cs(19,43): VRChat client runtime Udon exception detected! An exception occurred during EXTERN to 'TMProTextMeshProUGUI.__set_text__SystemString__SystemVoid'. Parameter Addresses: 0x00000003, 0x00000009 Object reference not set to an instance of an object.