Use a folder the signed-in account can actually write to; test saving a harmless file there before changing the scan destination.
- Scan fails when saving output
- In the Canon scan utility change the destination folder to a writable local or synchronized folder such as the configured Google Drive folder.
Reported outcome: Scans completed and saved.
Record the previous destination so it can be restored. Test the same scan and open the saved output, rather than treating the disappearance of an error as proof that a file was saved.