Resetting the volinfo.database
From time to time, my SuperDuper backups fail with the error “Could not enable permissions for volume __ : please restart your Macintosh”. Unfortunately, restarting doesn’t usually help. The fix is to delete the volume information database:
sudo rm /var/db/volinfo.database
The next time SuperDuper tries to enable ownership on the volume, the setting will stick, and SuperDuper will be able to complete the backup.
Update (2017-09-19): I think this fix is built into SuperDuper 2.9.2.
I've had to remove volinfo.database from time to time to solve problems with the ”ignore ownership on this volume” setting not sticking on external disks (as reported here and here).