What causes HTTP 502 Bad Gateway?

Upstream server is down or unreachable. Reverse proxy received a malformed response. Network issues between proxy and upstream server. Upstream server crashed.

HTTP 502 Bad Gateway

Server Error

The server, while acting as a gateway or proxy, received an invalid response from an upstream server.

Common Causes

Upstream server is down or unreachable
Reverse proxy received a malformed response
Network issues between proxy and upstream server
Upstream server crashed

How to Fix

Check if the upstream server is running
Review reverse proxy configuration (Nginx, Apache)
Check network connectivity between servers
Restart the upstream application server

Related Status Codes

500 Internal Server Error 503 Service Unavailable 504 Gateway Timeout

Need to look up other HTTP status codes?

View the Full HTTP Status Code Reference