The “522” error code is a unique code to inform website owners and visitors that the Cloudflare system is unable to connect to the hosting server in any fashion. After a certain amount of time, the Cloudflare system will stop trying to reach the server and will then display the “522” error.
The first places to check when you are presented with the 522 error:
Verify that the hosting server is able to accept web traffic. (ping the site IP)
Ensure that the domain’s DNS is properly configured so that the traffic is going to the correct location.
If the hosting server is responding and the DNS for the Domain is configured correctly, the issue may indicate a deeper issue. A few more common causes are listed below:
Blocked Cloudflare requests
When a server is attempting to handle too much traffic or is attempting to run too many processes the amount of resources allocation issued by the operating system to handle the traffic and processes can sometimes be overwhelming. When the resource allocation reaches an unstable level the server is no longer capable of efficiently providing the content that is being requested.
The level of efficiency is measured by a term called “Server Load.” This value represents the server’s capacity to continue to process new requests while handling the existing requests. Resource exhaustion can occur when the server is receiving so many requests that it just cannot allocate any more CPU or RAM to accommodate another process. When this happens the server will become unresponsive and Cloudflare detects that it is no longer getting traffic back from the server.
Alleviating high amounts of traffic or stopping local server processes will reduce the server load and allow the server to return to a more normalized state. When the server is able to accept new requests the Cloudflare service should then begin responding with the site content.
Blocked Cloudflare Requests
The most common reason for the 522 error code is that the hosting server may have proactive security measures that are falsely identifying the Cloudflare IP addresses as a threat. If that occurs check your .htaccess file, firewall, or other security features for denying rules that may contain the Cloudflare IP address. Once the deny rules are removed, Cloudflare should then be able to provide the content correctly.
Disabled Keep-Alive Header Option
Since the Cloudflare service uses a keep-alive header to maintain the site performance, there may be times where the keep-alive header option is disabled. If so, restoring the keep-alive functionality will allow the Cloudflare system to properly handle the requests. This option should be available on all of our Shared environments unless there is a specific rule for your site that is disabling it.