ORA-16461: database not flashed back or recovered to a consistent point
Cause:
ALTER DATABASE CONVERT TO STANDBY command failed because either the database was not properly flashed back to STANDBY_BECAME_PRIMARY_SCN, or at least one of the online data files was not current.
Action:
Flashback database to STANDBY_BECAME_PRIMARY_SCN and retry the ALTER DATABASE CONVERT TO STANDBY command.