Class & class type & not maintained in language &

What causes this issue?

You want to view a class hierarchy and have entered the number of a
class as a starting point for the hierarchy explosion. However, class
&V1&, class type &V2&, is not maintained in language &V3&.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Either maintain this class in language &V3& or choose a different
class.

Error message extract from SAP system. Copyright SAP SE.