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darkveins
Inspiring
July 29, 2025

Unity OpenXR Meta regression: passthrough doesn't work when focus is lost and regained

  • July 29, 2025
  • 2 replies
  • 367 views

Problem:
1. Passthrough initially works fine in the app.
2. Take the headset off, the display goes dark.
3. Put the headset back on, the display turns back on.
4. Unexpected: passthrough no longer works in the app!

Also, passthrough doesn't work in the first run after the app has been installed.

This is a regression. Passthrough always worked in the last version of the Unity OpenXR Meta package I used, which I think was 2.0.1.

Suspected Cause:
MetaOpenXRPassthroughLayer.Dispose() in the Unity OpenXR Meta package appears to be broken - it's not idempotent.
When Unity's OpenXRCompositionLayersFeature.OnSessionEnd() disposes it, the underlying resources are gone for good.
So when OpenXRCompositionLayersFeature.OnSessionBegin() creates a new one, it doesn't work.

Version:
Unity 6 (6000.0.51f1)
My selected XR plugin: Unity OpenXR Meta 2.2.0
Meta Quest 3

I think these packages are irrelevant to this problem, but including the versions anyway:
Meta XR Core SDK 77.0.0
Meta MR Utility Kit v77.0.0
Meta XR Platform SDK 77.0.0

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    2 replies

    jameswood32
    jameswood32
    Inspiring
    July 30, 2025

    Yeah, this seems to be a known issue with recent Meta/Unity OpenXR integrations. When the app loses and regains focus (like when removing the headset), the passthrough layer can fail to reinitialize properly. A temporary workaround is to manually re-enable the passthrough feature in code when focus is regained — you can hook into Unity’s OnApplicationFocus or OnApplicationPause. Hopefully, Meta or Unity will patch this in an upcoming release!"

      darkveinsAuthor
      Inspiring
      July 30, 2025

      Unfortunately, hooking into OnApplicationFocus doesn't work. The passthrough layer has already been improperly disposed of by the time this Unity method is invoked.

       I worked around this regression by creating a custom OpenXR composition layers feature. But it's a rather low-level solution that I don't imagine most devs are going to do.

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