What causes this issue?

Characteristic &V1& is the finest time in PartProvider &V2& (NCUMTIM),
or it is a validity slice characteristic, or &V1& is a compounding
parent of such a characteristic.
Therefore &V1& has to be mapped to a characteristic of Multiprovider
&V3&.

System Response

Characteristic &V1& is added invisibly to Multiprovider &V3& and for
Partprovider &V2& it is mapped to &V1&.

How to fix this error?

Check the definition of Multiprovider &V3&.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.