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Fixed in 2021.3.8f1, 2022.1.4f1, 2022.2.0a13



Found in




Issue ID




Crash on mono_class_get_flags when running various Unity processes



A recurring crash issue has been identified in Unity, affecting various workflows. Users have experienced crashes during project opening, closing, or building, asset importing, and periods of prolonged inactivity. The issue also manifests in operations like running projects in Play Mode or stopping it, working on animations, switching build settings, and so on. After a review of all relevant bug reports in our database, it has been concluded that this issue has been successfully resolved and no longer reproduces in active streams.

Reproducible with: 2021.3.7f1, 2022.1.3f1, 2022.2.0a12
Fixed in: 2021.3.8f1, 2022.1.4f1, 2022.2.0a13

Reproduced on: Windows 10, Windows 11 (by reporters)
Not reproducible on: No other environment tested

1. The common denominator in these reports is an assertion failure error logged as
"* Assertion: should not be reached at C:\build\output\Unity-Technologies\mono\mono\metadata\class-accessors.c:86"
2. The determination of the 'Fixed in' versions was made based on an analysis of the last known versions that were affected by the issue

First few lines of the stack trace:
0x00007FFC4C53567C (KERNELBASE) RaiseException
0x00007FFBAA2A064C (mono-2.0-bdwgc) [C:\build\output\Unity-Technologies\mono\mono\utils\mono-log-common.c:143] mono_log_write_logfile
0x00007FFBAA28C4A2 (mono-2.0-bdwgc) [C:\build\output\Unity-Technologies\mono\mono\eglib\goutput.c:172] monoeg_g_logv_nofree
0x00007FFBAA28C57C (mono-2.0-bdwgc) [C:\build\output\Unity-Technologies\mono\mono\eglib\goutput.c:215] monoeg_assertion_message
0x00007FFBAA28C5E6 (mono-2.0-bdwgc) [C:\build\output\Unity-Technologies\mono\mono\eglib\goutput.c:239] mono_assertion_message_unreachable
0x00007FFBAA2FE826 (mono-2.0-bdwgc) [C:\build\output\Unity-Technologies\mono\mono\metadata\class-accessors.c:86] mono_class_get_flags
0x00007FFBAA2F4195 (mono-2.0-bdwgc) [C:\build\output\Unity-Technologies\mono\mono\metadata\class-init.c:253] mono_class_setup_fields
0x00007FFBAA2F8852 (mono-2.0-bdwgc) [C:\build\output\Unity-Technologies\mono\mono\metadata\class-init.c:1768] init_sizes_with_info

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