Tried to upgrade one Cognos instance from 10.2.1 -> 10.2.2
Existing 10.2.1 works just fine.
Uninstalled 10.2.1 and installed 10.2.2 as per documentation. When trying to start the Cognos service i get a message i haven't seen before during upgrade.
CM-CFG-5024
The safest way to do the upgrade is to export the whole Content Store. Upgrade with a new/empty database and reimport the content.
This procedure will help guide you for the export and import the Content Store: