What is the meaning of HTTP status code 504?

HTTP status code 504 is a server error response code indicating that the server, acting as a gateway or proxy, did not receive a timely response from the upstream server (such as Tomcat, Nginx). This status code is known as HTTP 504 Gateway Timeout, which typically occurs when one server attempts to access data from another server but fails to complete within the allowed time. For example, if a web server forwards requests to another service and that service responds slowly, causing the request to time out, the gateway or proxy server may return a 504 error to the client. For development and operations teams, resolving 504 errors typically involves verifying the stability of the network connection to the upstream server, ensuring sufficient server performance, and confirming adequate resources to handle requests. Simple solutions may include optimizing server performance, increasing the server's timeout settings, or improving error handling strategies to better manage upstream service unavailability or delays.