Admins can no longer generate XML backups, if there is a lock held in the database by an invalid node ID. This is the error they get on the backup administration page UI if they try to generate the backup file.
Backup has not been performed as there is a backup or restore currently in progress. Please try again later.
Release the lock for the backup process in the DB if an invalid node ID is assigned to it.
Manually removing the lock held by the invalid node ID in the DB resolves the issue.