If you're seeing the error (Error From Intersoft:Error Code:E1437 Description:The Destination State / Territory is required) when trying to create a shipment with Royal Mail (Intersoft) then this would be due to the address information within the details of the order.
Please ensure the following fields have been populated with valid information:
Address Line 1.
Town.
County.
PostCode.
Country.
You may see the above error message if any of these fields are blank.
If you have populated the above fields with valid information and are still getting the error message, please create a new case online and reference the title of this article.