What Does HTTP Status 502 Mean? (Bad Gateway)
What HTTP 502 (Bad Gateway) Means In Plain English
A 502 status (Bad Gateway) means a gateway/proxy received an invalid response from an upstream server.
If you want the broader context across all status code families, use the full HTTP Status Codes Guide (2xx, 3xx, 4xx, 5xx).
Quick Navigation
- What HTTP 502 (Bad Gateway) Means In Plain English
- How to Read HTTP 502 in WebsiteDown Results
- Most Common Root Causes
- What to Do Next
- What to Avoid During Triage
- Real-World Examples
- HTTP 502 FAQ
How to Read HTTP 502 in WebsiteDown Results
When checker regions return 502, your edge path is reachable but upstream services or handoff behavior are failing. Focus on proxy-to-origin links.
If you see this code only in one region, compare with official provider status and retest from another network. Mixed regional results often indicate routing, policy, or edge differences rather than full global outages.
For deeper triage, compare this with the HTTP 504 guide, HTTP 500 guide, and the origin vs edge decision tree.
Most Common Root Causes
- Upstream service crashes or invalid responses.
- Protocol mismatch between proxy and origin.
- Stale upstream pools or broken health-check routing.
- CDN/edge path issues to origin during regional incidents.
What to Do Next
- Identify where 502 is generated (CDN, load balancer, reverse proxy).
- Compare upstream health and response validity by region.
- Review deploys affecting proxy config and upstream targets.
- Validate TLS/protocol compatibility across hops.
What to Avoid During Triage
- Do not treat 502 and 504 as identical.
- Do not restart healthy origins before verifying gateway layer evidence.
Real-World Examples
- Example: CDN PoP cannot complete handshake to origin and emits 502.
- Example: Nginx upstream points at wrong port after deploy.