Unity Editor Crash During Play Mode with Link and Hand/Body tracking

Description:

Since updating to Meta Horizon Link v85.0.0.239.552, developers using Unity 6 experience an immediate Crash to Desktop upon entering Play Mode. The crash occurs during the initialization of XR tracking subsystems. The error is originating from XR_EXT_hand_tracking.dll and/or XR_FB_body_tracking.dll located in C:\Program Files\Meta Horizon\Support\oculus-runtime\client-plugins\x64\.

Environment Details:

• Unity Version: Unity 6.2 (6000.2.14f1)
• Meta Horizon Link Version: 85.0.0.239.552 (85.0.0.239.552)
• Horizon OS Version: 2.3 (Build 5208318.1010.520)

Error Signature:

• Exception Code: 0xc0000409 (Stack Buffer Overrun)
• Faulting Modules: XR_EXT_hand_tracking.dll and/or XR_FB_body_tracking.dll
• Path: C:\Program Files\Meta Horizon\Support\oculus-runtime\client-plugins\x64\

Workaround: The .bak Method

If you are encountering this crash and need to continue development using controllers, you can "hide" the unstable tracking DLLs from the Unity Editor. This bypasses the memory fault during the Play Mode handshake.

1. Close Unity and the Meta Horizon Link PC app.
2. Navigate to: C:\Program Files\Meta Horizon\Support\oculus-runtime\client-plugins\x64\
3. Locate XR_EXT_hand_tracking.dll and XR_FB_body_tracking.dll.
4. Rename them by adding .bak to the end (e.g., XR_EXT_hand_tracking.dll.bak).
5. Restart Unity.

Note on PTC: This version (85.0.0.239.552) is currently circulating in the Public Test Channel. If you are enrolled in PTC, opting out may roll you back to a stable version, though the .bak method is a faster fix for those who need to stay on v85/Horizon OS 2.3 for other features.

Note on Builds: This only affects the PC Link Runtime used for Editor Play Mode. Native Quest builds (.apk) are unaffected as they use the headset's internal drivers; tracking will function normally on-device.

Link to first access post of same issue