Cause
The username/password used by the observer to log on to the primary database and Fast-Start Failover target standby database does not have valid SYSDBA credentials.
The username/password used by the observer to log on to the primary database and Fast-Start Failover target standby database does not have valid SYSDBA credentials.
Make sure the primary database and Fast-start failover target database are using a remote login password file. Make sure the SYSDBA password is the same at both databases and that the SYSDBA password is used in the CONNECT command. Start the observer again.
Try the following links for this error:
http://docs.oracle.com/cd/E16655_01/server.121/e26079/dgmus.htm
https://community.oracle.com/message/10165765
https://community.oracle.com/message/9791833
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