This is what I’m seeing in traceback.txt in the bug reports you uploaded:
Error: [WinError 32] The process cannot access the file because it is being used by another process: 'CHAMBER_DELICATE_STRUCTURE1.msh'
File "C:\Users\juu\.conda\envs\mfix-21.3\lib\site-packages\mfixgui\mesh.py", line 269, in generate_mesh
os.unlink(mesh_file)
So, it is a matter of the file being open in another process. I’ll look into why this is happening. It’s a bit odd that this message doesn’t match what’s in the screenshot you posted (WinError 5 vs WinError 32), but I suspect that it’s related.
– Charles