Oracle Error Message
ORA-16140: standby online logs have not been recovered
Reason for the Error
The standby database has online logs containing redo that has not been recovered. Activating the standby would lose redo contained in the online logs.
Solution
To recover the standby online logs issue the following command: ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH. Then reissue the ALTER DATABASE ACTIVATE STANDBY DATABASE command. To activate the standby without recovering the online logs, issue the following command: ALTER DATABASE ACTIVATE STANDBY DATABASE SKIP STANDBY LOGFILE.