HTTP 504 Gateway Timeout — Meaning, Causes & How to Fix

Code

504

Name

Gateway Timeout

Class

5xx Server Error

Specification

RFC 9110 §15.6.5

Cacheable by default

Only with explicit Cache-Control / Expires

What HTTP 504 means

504 Gateway Timeout is returned by a proxy, load balancer or CDN when the upstream server did not reply within its time limit. The upstream may still be working on the request, so the operation could have partly completed.

Common causes

• Slow database queries or long-running scripts.
• Upstream server overloaded or hung.
• Proxy timeouts set lower than the app needs (e.g. nginx proxy_read_timeout, default 60 s).
• A CDN timeout waiting for the origin.

How to fix it

For site owners

• Find the slow request in the app logs and optimise it (indexes, caching).
• Move long jobs to background workers and return 202.
• Raise proxy timeouts only as a last resort.

For visitors & developers

• Retry after a short wait — but be careful repeating payments or orders, they may have gone through.

SEO impact

Timeouts count as server errors for Googlebot: they reduce crawling, and slow servers get crawled less. Persistent 504s can drop URLs from the index.

Example 504 response

HTTP/1.1 504 Gateway Timeout
Server: nginx
Content-Type: text/html

Related status codes

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