ErrorFindly
5235xx Server ErrorCritical

HTTP 523 Origin Is Unreachable

Defined in Cloudflare

What Does HTTP 523 Mean?

Cloudflare could not reach the origin server, typically due to DNS resolution failure or the origin being offline.

Common Causes

  1. 1DNS records in Cloudflare pointing to invalid IP
  2. 2Origin server completely offline
  3. 3Origin IP address has changed
  4. 4Network path to origin is broken

Impact

  • ⚠Website completely unavailable
  • ⚠Cloudflare error page displayed

Developer Fix

For web developers and application engineers

  1. 1Verify DNS records in Cloudflare dashboard are correct
  2. 2Check origin server is online and reachable
  3. 3Update DNS if origin IP has changed

Server Admin Fix

For system administrators and DevOps engineers

  1. 1Verify and update Cloudflare DNS A/AAAA records
  2. 2Ensure origin server is online and accessible
  3. 3Check for ISP or hosting provider outages
  4. 4Verify origin IP hasn't changed

Frequently Asked Questions

How is 523 different from 522?
522 means Cloudflare can reach the IP but the connection times out. 523 means Cloudflare can't reach the origin at all — the IP is invalid, unreachable, or the server is completely offline.
How do I fix a 523?
Log into Cloudflare, check your DNS records, and verify the origin IP address is correct and the server is online. If your hosting provider changed your IP, update it in Cloudflare.

Related HTTP Status Codes

521Web Server Is Down522Connection Timed Out502Bad Gateway

About the Author

Web Infrastructure Team

Verified against official RFC specifications and real-world server configurations. HTTP status code behavior confirmed across Apache, Nginx, and Cloudflare.