I've taken on two ee cartthrob sites running off an msm installation. I just moved them to a Nexcess server and updated EE from 2.2.1 to 2.7.2 (and CT from 2.051 to 2.4). Everything is working fine until I try to post data through to sagepay (using the europe offsite option, so no ssl). Every single time I try to proceed to payment, I get this error on the payment confirmation page (without going out to sagepay):
Failed: sage_invalid3037 : The NotificationURL is too long.
I've investigated this thoroughly and have found that some people have solved it by correctly configuring a file called 'extload.php' that handles external payment gateways. However, I've edited this file with correct absolute server paths and msm site id's in both theme folders and I'm still getting the error. I can't get a call scheduled with the cartthrob guys for another two days (and that's the paid for option!) so I'm hoping there may be someone else in the community that has experienced and fixed this issue...?
I'm using cloudflare as a CDN, I don't know if this will have any implications?
I've also tried watching the http headers as I click the 'proceed to payment' button, but can't see anything interesting in there (except Cloudflare giving me a Temporary 302 on the confirmation page that delivers the error).