ORA-16139: media recovery required

admin

ORA-16139: mediarecovery required
Cause: An error has occurred while performing a switchover.
Action: Ifyou were switching a primary database to the standby role, the
conversion was successful, but one or more errors occurred after the conversion
completed. See the alert log for more information. You can proceed withswitching
the target standby database to the primary role, but you must address theerrors
reported at the old primary database before it can protect the new primary
database. If you encountered this error while switching a physical standby
database to the primary role, the switchover did not succeed because additional
redo must be applied. Verify that redo apply is active and wait until the
SWITCHOVER_STATUS column of the V$DATABASE dynamic performance view
reports TO_PRIMARY or SESSIONS_ACTIVE before retrying the switchover.