How to fix the Oracle error ORA-15158: rolling upgrade prevented by string?

In this post, you’ll learn more about the Oracle ErrorORA-15158: rolling upgrade prevented by string with the details on why you receive this error and the possible solution to fix it.

Oracle Error Description

ORA-15158: rolling upgrade prevented by string

Reason for the Error ORA-15158: rolling upgrade prevented by string

One or more instances were blocking the rolling upgrade.

How to fix the Error ORA-15158: rolling upgrade prevented by string ?

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

Terminate or wait until the reported operation is complete before attempting the rolling upgrade to the cluster.