ORA-16894
The property PrimaryDatabaseCandidates does not contain current primary database.
Cause
A switchover or failover operation was performed using SQL*Plus, or a failover was performed to a database that is not specified in the PrimaryDatabaseCandidates configuration property.
Action
When Data Guard broker is used to manage a Data Guard configuration, use DGMGRL or Oracle Enterprise Manager to perform switchover and failover operations. If this error was returned after doing a failover operation, a failover was attempted to a standby database that had not been specified in the PrimaryDatabaseCandidates configuration property.