Here is are the most common errors:
Invalid 4020: Information received from an Invalid IP address.
The Sage Pay system will only accept registration POSTs from servers whose IP Addresses have been registered with them. If they receive a POST from any other server, you will see this error message. You need to add the server IP.
Malformed 3034: The Vendor or VendorName value is required.
The Vendor field should contain the vendor name supplied by Sage Pay. It will only ever be able to contain a maximum of 16 characters consisting of numbers and letters with no spaces or unusual characters.
Invalid 3140: TheDeliveryCountry value is invalid
On WooCommerce make sure you have set up shipping methods, The shipping data is missing because there is no shipping option in WooCommerce
You should also be aware that:
- The MySagePay system tells you what errors have occurred i.e. looking like “Invalid 3140” which you can lookup in the integration guide
- You’re best testing all of this in the “test” gateway first, but that you must recreate all settings on the live and repeat testing