Cartthrob with SagePay suddenly stopped working; error 4020

Question

An existing site running CT 2.5 and EE 2.7.3 with SagePay (server) has suddenly stopped working on the LIVE server.

Initially I thought it might be due to the recent SagePay API update to v3.0, so I have updated the gateway files provided by the new owners Vector Media Group but still no luck.

The error presented is as follows: "4020 : Information received from an Invalid IP address."

Previously this was working so I know the valid IP's were setup and were ok, so I'm not sure why else this error would be present?

Also, this error appears before getting onto the SagePay server, after submitting the checkout form to go to SagePay it stops and this error shows up.

Any ideas anyone please, I'm stumped at the moment?

To start with I'm looking for ideas without having to update both EE and CT please! Thanks in advance.

Answer 1

(I'm with Vector; we make CartThrob)

This error is coming directly from SagePay and honestly, is usually exactly what it sounds like: your server is making a request from an IP that's not whitelisted in SagePay's system, so they're rejecting it. Common causes of this include:

• You're using a VPS or cloud server and the IP has changed
• You're using a server that has different IP addresses to make outgoing requests than the ones used for DNS (this is common on some cPanel/WHM servers)
• Your IP has recently changed.

You should definitely consider contacting SagePay to see if they can somehow tell you what IP your requests are coming from so they can be whitelisted.