How to fix the Oracle error ORA-38855: cannot mark instance string (redo thread string) as enabled?

In this post, you’ll learn more about the Oracle ErrorORA-38855: cannot mark instance string (redo thread string) as enabled with the details on why you receive this error and the possible solution to fix it.

Oracle Error Description

ORA-38855: cannot mark instance string (redo thread string) as enabled

Reason for the Error ORA-38855: cannot mark instance string (redo thread string) as enabled

The standby switchover or failover operation failed because it needs to mark an instance (redo thread) as enabled. However, it had less than 2 online redo logs, which prevented it from being enabled.

How to fix the Error ORA-38855: cannot mark instance string (redo thread string) as enabled ?

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

Add more logfiles to the specified instance and retry the command.