Unity 2020.3.31 and 2020.3.30 iOS Metal Crash on Device if Multithread is ON

Unity Engine
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1

Hi, I’m currently developing a new App for one of our clients, it’s an AR App and the project its basically empty with just the Camera/Microphone/Storage Permission screen being in development.

The Permission scene, works perfectly in Editor and Android but crashes on iOS with this error:

#0 0x000000010999084c in BufferMetal::IsBusy(bool*) const ()
Thread 1: EXC_BAD_ACCESS (code=1, address=0x38)

Crash happens on iOS 15.3.1

If I build using Multithread OFF, it works fine (But I need it on).

I found this bug on other posts and Unity Bugs reports pages BUT it’s reported as solved (which of course it isn’t).

I’ve Updated the project to the latest version of Unity 2021, same problem.

Thanks!
Alessandro.

2

We’ve had our iOS builds crash with the latest 2020.3.30f1-3.31f1; presumably the same bug is manifesting in all Metal builds and the editor - we went back to 2020.3.27f1 for the time being. As neither details of the issue or the fix have been posted, I have no workaround to offer than going back a few versions until the fix is rolled out, I’m afraid.

Here’s the related issuetracker link of the editor crash, marked fixed in unknown future versions. I haven’t seen the crash in builds being acknowledged anywhere, but keep checking the release notes.

3

Thanks for your reply, I did go back to 2020.3.27 myself and it works fine, it’s weird because I have no problem in Editor but only on device.
Hopefully Unity fixes this ASAP.
Cheers,
Ale

4

Even in editor, it’s likely triggered only in special cases (and only on the macOS, and only when using Metal as the rendering API… YMMV. On Windows, there doesn’t seem to be any problem, and 2020.3.31f1 feels snappier than previous versions of the editor; we only rolled back the version on the build server.

If the problem persists for more builds, I’m sure we’ll see more developers reporting about their iOS versions crashing/hanging on scene load. Glad that 2020.3.27 works for you though, cheers. :slight_smile: