http Error 522 - Connection timed out - how to fix the error

The status messages are an integral part of the HTTP standard for transmitting web pages. They ensure correct exchange of information and provide a general categorisation of errors to indicate their cause. The error 522 "Connection timed out" has been increasingly occurring in recent years, partially due to external factors. Unlike other notifications such as the Error 404 "Not found", it is often difficult to clearly identify the trigger and resolve the malfunction.

How can status messages like the error 522 be interpreted?

When establishing a connection via HTTP, clients and servers exchange status messages that describe their state or the result of a request. These are three-digit sequences, where positive feedback or pure information have the format 1XX, 2XX, or 3XX, and error codes start from 400. The protocol distinguishes between problems caused by the client, such as the error 401 "Unauthorized", and those caused by the server. The latter start with a 5 and often indicate misconfigurations.

What lies behind the error 522?

The Error 522 "Connection timed out" occurs when the initial step of establishing a connection is successful, but the server does not send any further data within a specified timeframe. It often occurs in conjunction with the Content Delivery Network (CDN) Cloudflare or other providers, hence it is known on the internet as the Cloudflare Error. The error 522 can have various causes when combined with a CDN, including:

• Web server is offline or frozen
• Overload on the server prevents processing a request
• Firewall blocking the HTTP request or its response
• Incorrect settings for the server in the Domain Name System (DNS)
• Server blocking necessary Keep-Alive packets
• Incorrect routing through different networks leading to data loss

An issue when the error 522 occurs is its limited informativeness. It merely describes a state that occurs without providing a clear indication of its origin.

Why does the error 522 often occur when using Cloudflare?

The company Cloudflare offers its customers an IT infrastructure that serves as a reverse proxy server, delivering content from a website partially from its own cache as a buffer. As the service is always available, a client can establish a connection to it. However, if for any reason the underlying web server is unreachable, the CDN waits for its response to be able to deliver the missing content. After exceeding the deadline set in the configuration, it terminates the communication with error 522. The situation changes if a CDN is not used as an intermediary. In this case, no communication is established from the beginning, causing the attempt to terminate early with a general browser error message such as "Website is not reachable" or "Connection refused."

How to fix error 522?

At times, error 522 occurs due to temporary overload, for example, when a single node within the connection is overloaded. If it persists for an extended period and can be reproduced with multiple devices, the cause lies in a faulty server configuration. Since the issue, unlike error codes 400 to 499, is not on the client's side, only the administrator of a website can take action. The necessary steps include:

• Checking the available resources on the server
• Reviewing IP address filters in .htaccess files and the firewall
• Matching DNS and IP addresses between the server and the CDN
• Enabling Keep-Alive packets in the web server's configuration
• Reviewing log files for any specific events
• Contacting the web host's support and Cloudflare

Error 522 usually arises from faulty communication between the web server and a CDN like Cloudflare. If no faulty settings or other causes are found after an extensive search, a professional examination by an expert is necessary.

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