If you are receiving an error (The remote server returned an error: (400) Bad Request. InnerMessage:{"response":{"errors":[{"code":"128065","message":"Invalid invoice number. Valid length is 0 to 35 alphanumeric"}]}} Error: The remote server returned an error: (400) Bad Request.) when trying to generate a courier label for UPS, the issue is caused by the Order Number in Mintsoft being over 35 characters.
Please change this and retry generating the shipment for the order.