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Error code

523 — Origin is unreachable

Cloudflare cannot reach the IP address configured for the origin.

TopicComputer error codes → About 1 min read

523 — Origin is unreachable

Domain : Cloudflare

What does this error mean?

Cloudflare cannot reach the IP address configured for the origin.

Where can it appear?

This error may appear in application logs, client messages, monitoring systems or protocol traces. Keep the complete timestamp, request context and surrounding events before troubleshooting.

Likely causes

  • Origin web server availability or performance
  • Firewall or routing between Cloudflare and the origin
  • Invalid or delayed HTTP response from the origin

Checks and resolution

  1. Test the origin directly when possible
  2. Review web server, PHP/application and firewall logs
  3. Confirm DNS records and Cloudflare-to-origin connectivity

Caution : Avoid disabling security or proxying permanently before the origin cause is understood.

Related resources

Relevant topic Cloudflare returns 522 while the origin seems reachable The origin responds to some tests while connections from Cloudflare time out. Relevant topic 520 — Origin web server returned an unknown error Cloudflare received an empty, unexpected, or unparseable response from the origin server. Relevant topic 521 — Origin web server is down Cloudflare cannot establish a connection to the origin web server. Relevant topic 522 — Connection to origin timed out The TCP connection to the origin does not respond within the expected timeout. Relevant topic 524 — Origin processing timeout Cloudflare connected successfully but the origin did not return a response quickly enough.
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