ORA-16821: logical standby database dictionary not yet loaded
Cause: Logical standby apply had not finished loading the dictionary. This warning is flagged by the broker's health check mechanism. This error is also flagged by failover and switchover if the target standby database has not loaded its dictionary.
Action: Start SQL Apply on the logical standby database and wait for it to reach the APPLYING state.
https://support.oracle.com/
http://www.oracle.com/