CheckUpDown

 

HTTP Error 504 Gateway timeout

What is Error 504

A server (not necessarily a Web server) is acting as a gateway or proxy to fulfil the request by the client (e.g. your Web browser or our CheckUpDown robot) to access the requested URL. This server did not receive a timely response from an upstream server it accessed to deal with your HTTP request.

This usually means that the upstream server is down (no response to the gateway/proxy), rather than that the upstream server and the gateway/proxy do not agree on the protocol for exchanging data.

Fixing 504 errors - general

This problem is entirely due to slow IP communication between back-end computers, possibly including the Web server. Only the people who set up the network at the site which hosts the Web server can fix this problem.

Fixing 504 errors - CheckUpDown

Use of proxies and caching is increasing on the Web. Our CheckUpDown robot will always try to 'drill through' to the real computer that actually hosts the Web site, but we do not have complete control over where our HTTP request actually ends up. If only one link in the chain of computers dealing with our HTTP request is broken, then an error such as 504 can easily occur.

Please contact us (email preferred) whenever you encounter 504 errors - there is nothing you can do to sort them out. We then have to liaise with your ISP and the vendor of the Web server software so that they can review the flow of IP data traffic between various computers under their control. However this is not an easy error to sort out, because the ebb and flow of Internet traffic makes this type of error very transient.

504 errors in the HTTP cycle

Any client (e.g. your Web browser or our CheckUpDown robot) goes through the following cycle when it communicates with the Web server:

  1. Obtain an IP address from the IP name of the site (the site URL without the leading 'http://'). This lookup (conversion of IP name to IP address) is provided by domain name servers (DNSs).
  2. Open an IP socket connection to that IP address.
  3. Write an HTTP data stream through that socket.
  4. Receive an HTTP data stream back from the Web server in response. This data stream contains status codes whose values are determined by the HTTP protocol. Parse this data stream for status codes and other useful information.

This error occurs in the final step above when the client receives an HTTP status code that it recognises as '504'.

Most Common HTTP Errors

403 - Forbidden
404 - Not Found
500 - Internal Server Error
502 - Bad Gateway
503 - Service Unavailable

Other HTTP Errors

This link contains an overview and a list of other HTTP Errors

For quick access to other errors, use the links below:
300 Error Range: 300 301 302 303 304 305 306 307
400 Error Range: 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417
500 Error Range: 500 501 502 503 504 505

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