Using Sagepay gateway on a build and sorting the gateway integration. Works fine until we get to the actual payment processing and we get the error:
HTTP Status Code: 500 HTTP Status Message: The request was unsuccessful due to an unexpected condition encountered by the server. Error Code : 5006 Error Description : Unable to redirect to Vendor's web site. The Vendor failed to provide a RedirectionURL.
The return url is set on the cartthrob checkout form to return="checkout/order-completed"
I've edited extload.php and modified the settings to match our MSM setup. I've also asked the guys at CT if they have any guidance but figure SO is a good place as well.
The issue lies within a file called extload.php which resides within /themes/third_party/cartthrob/lib
As we're using MSM, we had to appropriately map the variables correctly and what we had wrong was the $EE_absolute_server_url where it was an an actual URL when it should have been a server path.