GR/GI slip number is relevant for Italy only

What causes this issue?

The plant for which you have activated the goods receipt/issue slip
number is not located in Italy.
However, assignment of GR/GI slip numbers is only relvant for Italy.
Italian legislation requires specification of a GR/GI slip
number in addition to the material document number for goods that
leave the plant.
In other countries, only the material document number is used. In the
standard system, the material document number is printed on the goods
receipt/issue slip.

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?

Only use the GR/GI slip number if legislation in your country requires
you to do so.
If you wish to specify an external document when entering a goods
movement, use the fields <LS>Material slip</> or <LS>Delivery note</>
for this purpose.

Error message extract from SAP system. Copyright SAP SE.