[Dan Lester]

Just an FYI, not sure if it's been talked about before. I was trying to create a bootable backup for an old machine, for which the internal disk was formatted MacOS Extended (Journaled). The backup was accidentally done on an SSD that had been formatted with the modern APFS. When the backup was done, I did option-restart to get the Mac Boot Manager, and the backup disk DIDN'T APPEAR! When I did it again after reverting the backup disk to MacOS Extended (Journaled), everything worked dandy. Make sure your backup disk is formatted the same way as the disk you're backing up! Now, of course, older Macs can't read APFS, but you'd think that when SuperDuper is making a backup to a disk that isn't formatted in a compatible way, it would complain.