HTTP status code 502 indicates "Bad Gateway", which is a wrong gateway.
When the server acting as a proxy or gateway receives an invalid response from the upstream server, it will return a 502 status code to the client. This usually means that the proxy server is unable to obtain a valid response from the upstream server and pass it to the client.
Under common circumstances, 502 errors may be caused by the following reasons:
The upstream server is temporarily unavailable or down: When the proxy server serves as the middle layer, if the upstream server In the event of a failure, overload, or unresponsiveness, the proxy server cannot find a valid response and will return a 502 error to the client.
Proxy server configuration error: The proxy server may be misconfigured and unable to correctly forward requests to the upstream server or obtain a valid response, resulting in a 502 error.
DNS resolution error: If the proxy server cannot correctly resolve the domain name of the upstream server, it will also cause a 502 error.
When the client receives a 502 error, it is recommended to take the following steps:
Check the network connection: Make sure there is a connection between the client and the proxy server The network connection is normal, and the network connection between the proxy server and the upstream server is normal.
Refresh the page or retry the request: Since the 502 error may be a temporary problem, you can try refreshing the page or resending the request to see if the problem can be solved.
Contact the website administrator: If you continue to encounter 502 errors, you should contact the website administrator or server administrator and ask them to check the proxy server configuration or the status of the upstream server.
To sum up, HTTP status code 502 means that the proxy or gateway server encountered a problem while obtaining a valid response, resulting in the inability to provide a valid response to the client.