Oracle Error Message
ORA-16649: possible failover to another database prevents this database from being opened
Reason for the Error
An attempt to open the primary database was made either after a failover occurred, or when it was likely to have occurred as the result of the primary being isolated from the fast-start failover target standby database and from the fast-start failover observer.
Solution
Check if a failover did occur. If fast-start failover is enabled, and a failover did not occur, ensure that connectivity exists between the primary database and either the observer or the target standby database. Then, try opening the database again.
