We are seeing the below error in the IP logs after rolling back the most recent CP.
Unknown name value [1442] for environment class {com.idmlogic.sigma.commonserver.types.PORTAL_VERSIONS]
Release : 14.4
When IP is upgraded, it updates the systemdata table with the new version ID. When you revert the CP then the version also needs to be reverted. For example, if you upgraded to 14.4.2 then the version ID is V1442 and if you reverted back to 14.4.1 then you will need to navigate to the systemdata table and update the version value now to V1441.
Location:
If you resolved the issues that caused the upgrade failure then reapplying the latest CP again will also remediate the start up failure.