What it means
A gateway or proxy did not receive a timely response from the upstream server.
Common causes
- Slow database queries or external API calls
- Proxy timeout shorter than processing time
- Upstream server unreachable due to network issues
How to fix it
As a client or visitor
Retry later; for long operations, ask whether the API offers asynchronous processing.
As the site or API owner
Speed up the slow path or move it to a background job; raise proxy timeouts (proxy_read_timeout) only to realistic values.
Example response
HTTP/1.1
HTTP/1.1 504 Gateway Timeout
Date: Tue, 07 Oct 2025 09:30:00 GMT
Server: nginx
Content-Length: 0Specification
FAQ
› How do I fix 504 Gateway Timeout in nginx?
Find why the upstream is slow; if long requests are expected, raise proxy_read_timeout and the app server's timeout together.
› Who returns 504, my app or the proxy?
The proxy, load balancer or CDN in front of your app, after waiting too long for it.