In Microsoft Dynamics NAV >>> Customer Card, a user enters the value of Bill-To Customer No. on the invoicing tab as the Value of Customer No. on the General Tab, the following error is triggered when user to use the customer:
Error message : “You must not specify Bill-to Customer No. in Customer customer no. = [nn]
Solution is to Clear the Bill-to Customer No., this is because Bill-to customer No. can only be defined where it is different from the customer No. in question.