Once you've determined why the upgrade failed, you can roll it back and restore your old cluster.
The rollback script removes all of the changes the upgrade script made to your cluster. It also restores your old cluster from backup, starts it, and performs a health check.
When the script finishes running, your cluster will be back to the state it was in before you ran the upgrade and will be running. You can then either rerun the upgrade process or restore your old cluster.
If you decide to rerun the upgrade process, you must rerun the merge script, as the merged version of bdd.conf wasn't included in the backup.
To roll back a failed upgrade: