A dotnet crash occurs sporadically with a sigsev or sigbus when running on Mac OS. This is in the dotnet executable itself, and can happen on commands like `dotnet build`, not just on executing the built assembly. in fact, this seems to be where it is most often seen.
This is happening very infrequently. For one a particular project, it is seem once or twice a week across thousands of dotnet invocations.
Based on an analysis of the dotnet diagnostics it appears to be a manifestation of this issue in dotnet https://github.com/dotnet/runtime/issues/119761#issuecomment-4780332027
This issue is fixed in this change https://github.com/dotnet/runtime/pull/129763, but that fix landed after the current version of dotnet in Unreal.
Steps to Reproduce
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-398886 in the post.
| 0 |
| Component | UE - Platform - Mac |
|---|---|
| Affects Versions | 5.8 |
| Target Fix | 6.0 |
| Created | Sep 24, 2026 |
|---|---|
| Updated | Sep 29, 2026 |