This post is a small summary of all the issues we hit during several upgrades. I hope to update it (actually not, you know).
1. Don’t loose your ASM diskgroup. If you have diskgroup with AU>1M read this first: “Alert: Querying V$ASM_FILE Gives ORA-15196 After ASM Was Upgraded From 10gR2 To 11gR2 with an AU size > 1M” [ID 1145365.1]. In my case I was lucky to salvage the diskgroup by running ALTER DISKGROUP DATA CHECK ALL REPAIR twice.
2. Remove ORA_CRS_HOME from your environment prior to upgrade, otherwise the message “ORA-29780: unable to connect to GPnP daemon [CLSGPNP_ERR]” will become your friend. Does anybody need it?
3. Check your environment for LD_LIBRARY_PATH before doing install/uninstall of XDB (XDB is required for ACL). Even you haven’t configured it into .profile – oraenv is smart enough to set it.
4. WMSYS.WM_CONCAT. It is undocumented internal function that Oracle changed to return CLOB instead of VARCHAR2. So read the document “Problem with WMSYS.WM_CONCAT Function after Upgrading [ID 1300595.1]” first and don’t get surprised if you’re using such undocumented things.
5. To be continued…
Good luck in patching!