Clear the upgrade directory from both servers before reattempting further upgrades using the command
rm -fr /var/log/sonus/upgrade/* under all the following conditions:
- Performing LSWU from a pre-5.1 version to a 5.1 or later version.
- There is a need to revert the upgraded server after a single server upgrade while the peer is still on an older version.
- A revert will be performed by doing a re-ISO.