Oracle Solution for Error ora-16666

ORA-16666: unable to initiate fast-start failover on a standby database

What triggered the Error:

The request to initiate a fast-start failover using DBMS_DG.INITIATE_FS_FAILOVER was made to a standby database. An application may only request that fast-start failover be initiated by calling DBMS_DG.INITIATE_FS_FAILOVER on a primary database.

What should we do to fix it:

Call DBMS_DG.INITIATE_FS_FAILOVER on the primary database.