ORA-16823
Real Time Query standby pluggable database is closed.
Cause
Redo apply services for this standby pluggable database that was in Real Time Query mode is stopped in response to the users attempt to either close the pluggable database or the database.
Action
If the database is in the process of closing, no action is necessary. Data Guard broker will start redo apply services once the database is restarted, or the pluggable database is opened. Alternatively, issue the DGMGRL command: EDIT PLUGGABLE DATABASE name SET STATE=APPLY-ON to start recovery at the mounted instance in non-Real Time Query mode.