A 504 Gateway Timeout error is a webserver’s code for: "I reached out to the upstream server for you, but it took too long to answer and timed out.".

How do I fix or troubleshoot a 504 Error?

Common steps include reloading the page in your browser, checking for typos in the URL, verifying server status, clearing browser cache or cookies, and contacting the website owner or server administrator if the error persists.

504 Error | Error-Message.Net

A 504 Gateway Timeout error indicates that the server, while acting as a gateway or proxy, did not receive a timely response from an upstream server it needed to access in order to complete the request.

While a 502 error means the upstream server sent a broken or invalid answer, a 504 error means the upstream server didn’t answer at all within the allotted timeout window.

Determining why

The backend server is overloaded with traffic and cannot keep up.
A database query or complex backend calculation is hanging or taking minutes to complete.
Network latency or packet drops between the proxy and the upstream server.

Steps you could possibly take:

Wait and retry - Refresh the page after a few moments. If the server was temporarily spiked, the load may subside.
If you are the website owner or server administrator:
- Increase proxy timeout directives (such as proxy_read_timeout in nginx or Timeout in Apache) if requests legitimately require extended compute time.
- Optimize slow SQL queries and add database indexes.
- Offload long-running operations (like bulk emails or video transcoding) to background worker queues rather than processing them synchronously inside web requests.

Source: RFC 9110 Section 15.6.5 (HTTP Semantics)