ORA-16897
start database to mount mode
Cause
This error was returned by DBMS_DG.SWITCHOVER because the database must be started to the mount mode to complete the switchover operation. Or, the error was returned from DBMS_DG.REINSTATE or DBMS_DG.CONVERT_TO_PHYSICAL when the database must be started to the mount mode to perform the operation.
Action
Start the database to the mount mode, wait for the database to start, and wait for the broker to complete initialization using DBMS_DG.WAIT(WAIT_BOOT, wait time in seconds). Then, for reinstate and convert operations, retry the operation.