How to fix the Oracle error ORA-16647: could not start more than one observer?

In this post, you’ll learn more about the Oracle ErrorORA-16647: could not start more than one observer with the details on why you receive this error and the possible solution to fix it.

Oracle Error Description

ORA-16647: could not start more than one observer

Reason for the Error ORA-16647: could not start more than one observer

The observer could not start because there was another observer already observing the Data Guard configuration for which fast-start failover may have been enabled.

How to fix the Error ORA-16647: could not start more than one observer ?

You can fix this error in Oracle by following the below steps

Stop the running observer. Retry the operation.