I am pretty sure Unity 6 has several issues with its burst processing but unfortunately I can not recreate them in any reliable manner.
Todays are these 2 TransientArtifactProvider errors popping up in the console after compiling:
Symbol file LoadedFromMemory is not a mono symbol file
- Loaded All Assemblies, in 1.024 seconds
TransientArtifactProvider::IsTransientArtifact call is not allowed when transient artifacts are getting updated
TransientArtifactProvider::GetArtifactID call is not allowed when transient artifacts are getting updated
The keyword “artifact” naturally reminds me of the Library. You may want to close the project, then delete the Library and Obj folders to remove any stale caches. Hopefully that resolves the issue.
Yes I’ll accept the library deletion answer, but also be prepared to re-install/upgrade some of the more complex plugins you may have as some things work differently in URP/HDRP in Unity 6 and so project upgrade seems particularly prone to ending with warnings and errors!