요약
A gateway or proxy received an invalid response from an upstream server.
언제 발생하나
Common when a reverse proxy’s backend is down or returns garbage.
흔한 원인
- Upstream / backend server is down
- Backend returned an invalid response
- Reverse-proxy misconfiguration
- DNS or firewall blocking the upstream
해결 방법
- Check the upstream/backend health
- Review reverse-proxy configuration
- Restart the backend service
- Verify upstream DNS and networking