Code 504

Gateway Timeout - RFC 7231

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.

sequenceDiagram participant User participant Gateway participant Backend Note right of Backend: Behind Gateway User->>Gateway: Initial request Gateway ->> Backend: Fowards request Gateway -->> Backend: Takes too long to respond Gateway --x Backend: Request fails Gateway -->> User: Returns 503 error