SteadyNode

Cloudflare · HTTP 523

Cloudflare Error 523: Origin Is Unreachable

Find the routing, address, or network fault behind Cloudflare 523. Verify the configured origin IP, public route, and address-family reachability.

Origin / Network Firewall

Decode a CDN or gateway error

Paste a captured HTTP response or enter a status and headers. Only the status and response headers are sent; common credential headers are filtered first.

Supports raw headers, full HTTP responses, JSON with status/statusCode and headers, cURL -v/-i response output, and HAR exports. HAR selects a server error first. cURL commands are never executed; request headers, response bodies, and common credential headers are excluded.

Diagnostic report

Error code / name

CF-523

Fault domain

Origin / Network Firewall

Why it happened

Cloudflare could not route traffic to the configured origin address. A stale origin IP, broken route, or unreachable IPv6 address can leave the edge with no working path.

Actionable fixes

  1. Compare the origin address in DNS and proxy settings with the currently assigned server address.
  2. Test IPv4 and IPv6 routes separately; remove an unusable address family only after confirming service requirements.
  3. Check provider routing and origin network ACLs from a public vantage point.

Why this error happened

Cloudflare could not route traffic to the configured origin address. A stale origin IP, broken route, or unreachable IPv6 address can leave the edge with no working path.

Actionable fixes

  1. Compare the origin address in DNS and proxy settings with the currently assigned server address.
  2. Test IPv4 and IPv6 routes separately; remove an unusable address family only after confirming service requirements.
  3. Check provider routing and origin network ACLs from a public vantage point.

Network failure point

Client -> Cloudflare Edge -> origin address lookup -> route unavailable -> X Origin

Verify origin directly via CLI

curl -sS -v -I --connect-timeout 5 --max-time 15 --resolve example.com:443:ORIGIN_IP https://example.com/health

Configuration fix

dns-zone.txtdns
origin.example.com. 300 IN A ORIGIN_IPV4_ADDRESS
origin.example.com. 300 IN AAAA ORIGIN_IPV6_ADDRESS

Catch this failure before it becomes an outage

SteadyNode's regional probes detect differences between origin addresses and public routes, while its HTTP checks confirm whether a corrected route restores service.

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Frequently asked questions

What is the difference between Cloudflare 522 and 523?

A 523 points to an unreachable origin route or address; a 522 indicates the edge attempted a connection but did not complete it in time.

Can an incorrect AAAA record cause a 523?

Yes. An unreachable IPv6 origin address can fail independently of IPv4, so test both address families.

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