Project manager operation unknown error

Hi,

i try to export my project to an external SSD. Just at the end of the process a window pops up with "unknown error" and "safe and retry". Of course i did, but it does not help. Closed and reopend. No change.

This was the first project after latest update.
Screenshot attached

v24.4.0.15
Macbook Pro M3 Max
Sonoma 14.3.1