HTTP 504 — Gateway Timeout
5xx Server Error
What it means
A proxy did not get a response from the upstream server in time.
What to do about it
The backend is too slow. Profile the slow endpoint, add a database index, or raise the proxy timeout — but a timeout is a symptom, and raising it usually just moves the problem.
Where it sits
504 belongs to the 5xx family: The server failed to fulfil an apparently valid request. The fix is on the server side.
HTTP/1.1 504 Gateway TimeoutChecking it yourself
# see the status code and headers only
curl -sI https://example.com/path
# follow redirects and print each hop
curl -sIL -o /dev/null -w "%{http_code} %{url_effective}\n" https://example.com/path
# JavaScript
const r = await fetch(url);
console.log(r.status, r.statusText);How this code behaves
| Cacheable by default | No — caches must not store this response unless explicit cache headers permit it. |
| Safe to retry | Yes, with backoff. This is a transient condition; retrying the same request is reasonable. |
| Effect on search indexing | Repeated server errors reduce crawl rate and eventually drop pages from the index. |
Returning 504 correctly
# nginx
return 504;
# Express
res.status(504).json({ error: 'Gateway Timeout' });
# Go
w.WriteHeader(504)
# Python (Flask)
return jsonify(error='Gateway Timeout'), 504;Frequently asked questions
What does HTTP 504 mean?
A proxy did not get a response from the upstream server in time.
How do I fix a 504 error?
The backend is too slow. Profile the slow endpoint, add a database index, or raise the proxy timeout — but a timeout is a symptom, and raising it usually just moves the problem.
Is 504 a client or server problem?
A server problem. The request was valid; the server failed to fulfil it. Nothing the client changes will help.