Looks like you found the answer yourself. For future reference, when upgrading and you have an existing database, ALWAYS do both a cold backup and a full export first, and ALWAYS create dynamic SQL scripts which can be used to restore tablespaces, users, roles, system privilege grants, any PUBLIC synonyms and database links, etc., in case you can't do a full import. Then you have the option to try the upgrade followed with a full import. If that doesn't work for some reason, as in migrations from 8.1.5 to 8.1.6, you can delete and re-install software, create empty database, run scripts to re-establish users, etc., and do an import at user-level. In case you decide not to proceed with upgrade and want to go back to a previous version, you can restore from your backup. And, of course, as soon as you determine your newly upgraded database is working okay, be sure to do a full backup. First rule in database CYA is backup before you start and again after you finish. It takes a little extra time, but it's worth the insurance.