Jeff the problem is not that a plugin is not working.
IT seems that when you restore a backup you need to be running exactly the same release version of discourse and have installed the same plugins you were running in the origin of the backup.
But when you recover a backup from time ago you don’t know exactly which versions and plugins you were running at that time.
It would be helpfull that you could list the version and plugins that were installed when the backup was made, from the backup file and seeing it in the restore interface.