GTIN &1 is already used in material &2. Registration code mismatch. &3/&4

What causes this issue?

This GTIN is already used for other materials. The registration code for
the current material is different from the registration code used in the
other materials. A synchronization of registration code between all
materials is not possible with the transactions MM01/MM02.

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?

To synchronize the registration code, save the materials without GTIN
assignment. Call transaction <NP>/STTPEC/TRD_ITM_SER</> to assign the
GTIN, and to synchronize the registration code for all materials using
this GTIN.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.