Failed to deserialize Udon Program
available in future release
BlueAmulet
Several Udon scripts in my world seem to have a chance of breaking on load, where some people reported the respective feature working properly, while others reported it being broken. I was able to reproduce the issue finally and found several of the programs reporting the following:
[SerializedUdonProgramAsset] Failed to deserialize Udon Program due to an exception:
System.InvalidOperationException: Operations that change non-concurrent collections must have exclusive access. A concurrent update was performed on this collection and corrupted its state. The collection's state is no longer correct.
[UdonBehaviour] Could not load the program; the UdonBehaviour on '(Name)' will not run.
Relevant section of log attached.
Log In
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available in future release
Provania
I had this issue with a couple worlds when udon debug logging was turned on. This includes the doors in eco-echo, and b club 4 had all of it's UI break completely.
Turning it back off however, made these things more likely to work.
BoatFloater
I am seeing this in a few worlds too, always on the same asset. Even if I re-build the world or change SDK versions. Whether it happens or not is inconsistent each time I join the world.
Haxy
Can confirm, able to reproduce with better chances in bclub 4
Also ran into it in Rainbow Library, Haxy Airship
Both are either from VRC.Udon.UdonBehaviour.PreloadUdonProgram or VRC.Udon.UdonBehaviour.LoadProgram
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_tau_
tracked
Roughy~
I am also encountering this problem in a world I'm working on. It has a tendency to break the same asset every time, but will occasionally break another one instead. The error message is always the same, just affecting a different script.
The problem did not occur prior to the past couple of days.
Problem has a roughly 80% chance of occurring on any given join.
Testing with other users suggests a 70%+ chance of breaking the same script every time.
Inspecting logs of other users after noticeable world-breakage occurred confirmed the same issue affecting a different, critical script instead.
The problem also occurs in offline mode.
VRChat Build: 2025.2.1p1-1627-4c6059424e-Release
wrld_a799d870-47a8-4563-861f-a082834cb075 ( private )
BlueAmulet
Checking through my logs I have seen this issue occur in other worlds besides mine. Another world where I experienced a "Failed to deserialize Udon Program" in was Avatar Testing Chamber by Ziggor (wrld_a5e9ec13-36b1-4e63-ae0c-dab9023401f9)
｜KitKat｜
Can you provide a link to the impacted VRChat world?
BlueAmulet
｜KitKat｜Affected world is wrld_5129136a-c052-4a53-851b-4529b4512c09. Notable issue is light probes are supposed to update as the player walks into different rooms. When the bug is happening, the room tracking doesn't work and treats the player as if they're always in the spawn room. And again the bug is inconsistent to trigger, sometimes the scripts will load, sometimes they will fail to deserialize.