What causes this issue?

You have tried to enter data that is either not defined or is invalid
for &V1&.

System Response

You cannot continue entering data.

How to fix this error?

Enter valid data or discontinue the activity.
The error might have occured because the combination of country/
transportation zone has not been correctly maintained in the master
data for the selected location, or that required data is missing.

Error message extract from SAP system. Copyright SAP SE.