Country &1 does not exist - please correct

What causes this issue?

Country &V1& is not defined.

System Response

Country &V1& is not allowed.

How to fix this error?

Correct your entry.
Use the entry help for finding the allowed countries.
Or remove your entry.
If you need country &V1&, you have to first enter it in Customizing
with the necessary meaning. Contact the person responsible for
Customizing.

Error message extract from SAP system. Copyright SAP SE.