ORA-20603: Updating timezone region of a target is not supported

Enterprise manager does not start after updating the database. The emdb.nohup has an ORA-20603: Updating timezone region of a target is not supported error message in it.

The problemThe timezones have been updated within the database.

SolutionAs Oracle run:

$ORACLE_HOME/bin/emctl resetTZ agent

and follow the instructions.  You'll need the sysman or sys password to make the changes.