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HTTP 502 Bad Gateway — Upstream Server Error

Critical5xx server error

Overview

HTTP 502 Bad Gateway means a gateway or proxy received an invalid response from the upstream server.

Key Details

  • Status: 502 Bad Gateway
  • Category: 5xx Server Error
  • Proxy/gateway received invalid upstream response
  • Usually a backend server issue

Common Causes

  • Backend server crashed or is down
  • Upstream server returned an invalid response
  • Load balancer cannot reach backend
  • PHP/Node/Python process died

Steps

  1. 1Wait and retry — often temporary
  2. 2Check if the backend server is running
  3. 3Review upstream server logs
  4. 4Verify load balancer and proxy configuration

Tags

http-status5xx-server-errorhttp-502httpstatus-code

More in 5xx Server Error

http-500-internal-server-errorHTTP 500 Internal Server Error — What It Means & How to Fix It
Critical
http-501-not-implementedHTTP 501 Not Implemented — What It Means & How to Fix It
Critical
http-502-bad-gatewayHTTP 502 Bad Gateway — What It Means & How to Fix It
Critical
http-503-service-unavailableHTTP 503 Service Unavailable — What It Means & How to Fix It
Critical
http-504-gateway-timeoutHTTP 504 Gateway Timeout — What It Means & How to Fix It
Critical
http-505-http-version-not-supportedHTTP 505 HTTP Version Not Supported — What It Means & How to Fix It
Critical

Frequently Asked Questions

Usually the backend application crashed or is overloaded.