by Tim Lovett.
Hmmm. And when I remove (uncheck) stuff like "blocks" and things (I really only want quiz results), I got a successful backup.
In the next screen that lists the backup files, the previous (default) backup was there! After downloading and restoring that previous one in another Moodle site it seemed to work fine. So is Moodle throwing the error even though the backup file was written OK??? Sure looks like it to me.