Use only local packets due to inheritance for object type '&'

What causes this issue?

You tried to reassign an object type to a packet that only contains
transportable objects. However, an inheritance relationsip with an
object type which is only available locally in this system is defined
for this object type. To avoid transport problems, it is not permitted
to define transportable object types as subtypes for local object
types.

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?

Select a local packet for the object type, or reassign the supertype
first to a transportable packet.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.