HTTP 504 Gateway Timeout

What does HTTP 504 mean?

A gateway or proxy did not get a response from the upstream server in time. The application is reachable but too slow: the proxy gives up after its timeout (60 s by default in Nginx proxy_read_timeout; 100 s at Cloudflare; 10–60 s on serverless platforms).

5xx Server error: The request looked valid, but the server failed to fulfil it. The fix is on the server side.

Common causes of a 504 error

• Slow database queries or external API calls.
• Long-running requests such as reports or imports done synchronously.
• Serverless function time limits.

How to fix 504 Gateway Timeout

• Optimize slow queries and add caching.
• Move long tasks to background jobs and return 202.
• Raise proxy timeouts only as a last resort.

How to find the cause of a 504

A 504 means your app is too slow for the proxy’s time limit, so time the app directly.

curl -o /dev/null -s -w 'total: %{time_total}s\n' http://127.0.0.1:3000/slow-page
sudo tail -n 30 /var/log/nginx/error.log

If the direct request is slow, fix the slow query or outside call. Raising the limit, such as proxy_read_timeout 120s; in Nginx, only helps for work that is meant to take long. Move long jobs to the background instead.

504 and SEO

Slow responses hurt Core Web Vitals and crawling; persistent 504s cause deindexing like other 5xx errors.

Example response

HTTP/1.1 504 Gateway Timeout

How to return a 504 response

Node.js (Express)

res.status(504).json({ error: 'Gateway Timeout' });

PHP

http_response_code(504);

Python (Flask)

return {'error': 'Gateway Timeout'}, 504

Go (net/http)

w.WriteHeader(504)

nginx

return 504;

Related status codes

• 502 Bad Gateway — A gateway or proxy got an invalid response from the upstream server.
• 503 Service Unavailable — The server is temporarily unable to handle the request.
• 408 Request Timeout — The server timed out waiting for the client to send the request.
• 524 A Timeout Occurred — Cloudflare connected to the origin, but it did not send a response within 100 seconds.

Check which status code a URL returns with the HTTP header checker.