16649, 0000, "possible failover to another database prevents this database from being opened"
*Cause: 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
*Action: 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.