Vendor & does not exist.

What causes this issue?

The system could not find purchasing data in the master data for
customer &V1&.

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?

Check if the customer number which was entered is correct.
Maintain customer master data in Transaction <DS:TRAN.VD02>VD02</>.

Error message extract from SAP system. Copyright SAP SE.