5xx Server error
HTTP 504 Gateway Timeout
A server working as a gateway or proxy didn’t get a response in time from the server behind it. The application may still be working on the request, or may have hung.
Defined in RFC 9110, section 15.6.5(opens in a new tab)
//_01 Uptime checks
Is 504 up or down for a monitor?
Uptimecheck HTTP monitor
Default settings
Down. It is outside the default 200–399 range, so a monitor reports an outage once a second check confirms it. If 504 is the answer you expect from that URL, add it to the monitor’s expected status codes.
Is it down? checker
Free, at /is-it-down/
Down. A 5xx means the server, or something in front of it, failed to answer.
//_02 Causes and fixes
Why you see 504 and what to do
Typical causes
- Slow database queries or long-running scripts.
- An overloaded application server.
- Network problems between the proxy and the application.
If you run the site
- Find the slow requests and speed them up, or move long jobs to a background queue.
- Raise the proxy’s timeout only for requests that legitimately take long.
If you’re a visitor
- Try again in a few minutes.
Know the moment your site stops answering as it should
An Uptimecheck monitor requests your page as often as every minute, checks the status code against the ones you expect, confirms a failure with a second check and then alerts you.
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Questions
What does HTTP 504 mean?
A server working as a gateway or proxy didn’t get a response in time from the server behind it. The application may still be working on the request, or may have hung.
Does an uptime monitor count 504 as down?
Down. It is outside the default 200–399 range, so a monitor reports an outage once a second check confirms it. If 504 is the answer you expect from that URL, add it to the monitor’s expected status codes.
Downtime is obsolete.
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