Callback 503 errors with PSP Card Gate in WordPress

When customers paid (or failed) the PSP is sending a callback to the webshop sending it the status of the payment. This callback receives an 503 error as soon as CloudFlare is turned on. Even if CloudFlare proxy is switched off (the orange cloud made grey) it still returns the 503 error.

The only solution known right now is to switch the NS back and no longer point it to CloudFlare.

What i’ve tested:

    1. When we open the callback url to test in a browser we don’t get a 503 error. That is likely to be because the CF proxy already let us pass trough.
    1. When we test the callback from the Card Gate panel we get instantly the 503 error: Received HTTP code 503 from proxy after CONNECT

What Card Gate states:
They are known of customers having problems with CloudFlare but have no solution

What CloudFlare states:
They point to this article WooCommerce Worldpay handshake_failure Not Completing Order but this is out of our span of control

I truly hope that CloudFlare and CardGate can find a solution for this.

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Tested the last days and with our test environment we could reproduce, but after last weekend the problems were gone and the 503 error no longer occurred. Now we activated in on a live site and it worked for 2 hours… after that suddenly the 503 errors occur again.

When you open the callback url in your browser there is no error, when we resend it through the platform of our PSP the error occurs.
Received HTTP code 503 from proxy after CONNECT

We’ve whitelisted the ip’s from our PSP for all our sites and have not changed this since yesterday… no clue why the 503 happen on the Proxy side.

Can you share the domain where this is happening?

Is cloudflare mentioned in the error? A 503 indicates rate limiting by the host, but if it’s a connection limit in a Cloudflare data center the error should include cloudflare.

Hi Cloonan,

Thank you taking the time to look into this. Domain is

  1. when we change the NS back and away from CloudFlare this error does not occur
  2. i’ve checked the server error and access logs but the 503 does not occur on the server side. When I send the callback it never arrives at our server
  3. as far as i can see (i’m just a customer of Card Gate and have no server access on their side) this is the error

We’ve also tested with this demo site, and this site is still receiving the calls ( with no 503 errors. Because the call never reaches the server I can’t do anything here.

Hi Cloonan,

Since yesterday evening 16 call where fired… 2 callbacks did reach our server, 14 did not. one of the lucky few. If i retry the same callback i get an error:

Hope to hear from you soon

PS: i would love to send you the complete POST callback but there is personal information in it so I can only share this in a private channel.

No idea what changed, while searching our serverlogs all calls are since CET+1 9:30 are coming through without the 503 error. We’ve just resend the callbacks of all failed orders and they also reached our servers.

To be sure I also today checked our server logs for callbacks from the PSP. The one that worked are in the logs and give a 200. No where (yes, i did check the error logs as well and the general server logs) the failed callbacks can be found. This makes me more and more sure that they were not parsed from CF to our server.

I’m digging internally to see if I can find disruptions and/or recent changes.

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