// http 5xx · server error
HTTP 502 Bad Gateway
An upstream server returned an invalid response.
What HTTP 502 Bad Gateway means
502 Bad Gateway means a server acting as a proxy or gateway got an invalid response from the upstream server it relies on. The immediate server is fine; something behind it failed.
Which category is it?
502 is a 5xx code — Server error. 5xx means the server failed to fulfil an apparently valid request. It's the server's responsibility, not the caller's.
Common causes
- The upstream/origin server is down or crashed
- A misconfigured reverse proxy or load balancer
- The upstream returned a malformed response
How to fix it
- Check the health of the upstream service
- Verify proxy/load-balancer configuration
- Restart or redeploy the failing origin server