Library default set & has been assigned characteristic &

What causes this issue?

Sets which you want to use as library default sets must be created for
the appropriate characteristic. This is not the case here.

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?

Check the set ID and select a set that has been created for the
appropriate characteristic. If you do not know any valid set IDs, press
F4 to display possible entries.

Error message extract from SAP system. Copyright SAP SE.