&1 characteristics, &2 MG objects and &3 classifications were transported

What causes this issue?

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

System Response

How to fix this error?

Please check the correctness of the data you just transported in the
receiving system. In particular, please note that no new materials will
be created for the material group. You need to do this manually using
transaction WG02. In addition, you should check the hierarchy with the
corresponding information transactions from the Material Group menu.

Error message extract from SAP system. Copyright SAP SE.