How to fix the Oracle error ORA-15155: version incompatible with the cluster?

In this post, you’ll learn more about the Oracle ErrorORA-15155: version incompatible with the cluster with the details on why you receive this error and the possible solution to fix it.

Oracle Error Description

ORA-15155: version incompatible with the cluster

Reason for the Error ORA-15155: version incompatible with the cluster

The current software version of the instance was incompatible with the other members of the cluster.

How to fix the Error ORA-15155: version incompatible with the cluster ?

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

Make sure that all the members of the cluster are at the same version. If you are attempting to perform rolling upgrade, execute ALTER SYSTEM START ROLLING command. Ensure that the version being upgraded to is compatible with the existing version of the cluster.