GTIN &1 already used in material &2. Ser. Type lower than &3 not allowed

What causes this issue?

This GTIN is already used for other materials. The serialization type
for the current material is different from the serialization type used
in the other materials. A synchronization of serialization types between
all materials is not possible with the transactions <NP>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 serialization types, save the materials after
reverting to the previous values. Call transaction <NP>/STTPEC/TRD
_ITM_SER</> to synchronize the serializations types for all materials
using this GTIN.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.