The issue is that the BOM script doesn’t exist where kicad thinks it should.
You should be able to dig around and find the actual path where the script lives, and update the command line at the bottom to the real path. I don’t have a Windows build handy or I’d check what the path should be and tell you. You can try hitting the “+” button and see if that opens a browse window in the right location.
As an experiment, see if clearing your preferences fixes the problem. BOM script paths are saved in your preferences, so if the BOM scripts moved recently but your preferences still point to the old location, there will be an issue. On Windows I think your preferences are in %APPDATA%\kicad - you can backup that folder and then remove it to start with fresh preferences.
If that fixes the issue, make a note of where the BOM script is located, then you can restore your preferences and update the script path in that dialog.
If that doesn’t fix it, it’s probably a bug. Open an issue on gitlab so the bug will get fixed. There won’t be an update to fix this unless someone reports it.