We are running a great training this week in Munich, called TECH CHALLENGE for Oracle people only. And one group hit the below issue so I thought I should share this as it is very likely it will happen with the upgrade to Oracle Database 12c in your environment as well.
During the run of catctl.pl or DBUA you may get an error saying:
ORA-20000: Unable to gather statistics concurrently:
Resource Manager is not enabled.
ORA-06512: at “SYS.DBMS_STATS”
Even worse, the upgrade will fail and exit in phase 68 of the parallel upgrade.
This issue is new with Oracle Database …