HTTP 504 — Gateway Timeout
The server was acting as a gateway or proxy and did not receive a timely response from the upstream server
When to use it
Use status 504 when this is the correct HTTP response semantic: The server was acting as a gateway or proxy and did not receive a timely response from the upstream server
Request and response example
GET /reports/export HTTP/1.1
Host: api.example.com
HTTP/1.1 504 Gateway Timeout