Your project file is corrupted, and can’t be fixed.
This file is corrupt and it has nothing to do with the upgrade. The only way to recover is if you have a backup. You can read more about it by searching here on “NUL” or the web in general on “windows file null character” to find something like this . As far as we can tell this is not due to a bug in Shotcut but something in the way Windows does caching or hardware. Shotcut first writes a temporary file, verifies it valid XML, and then renames it to the name you provided.
