523 Origin Is Unreachable

Cloudflare could not find a network route to the origin server.

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Status code523
Status textOrigin Is Unreachable
Category5xx Server Error
Response has bodyUsually
Defined byCloudflare (not an IANA-registered code)

What does 523 Origin Is Unreachable mean?

Cloudflare could not find a network route to the origin server. It is numbered in the 5xx Server Error range but is not a registered HTTP status code, so the general meaning of that class is only a rough guide to it.

When do APIs return 523?

On sites behind Cloudflare, when the origin's address cannot be reached at all. The usual cause is a DNS record that points to an IP address the server no longer has, for example after a move to a new host. A routing problem between Cloudflare and the hosting provider produces the same result.

How to fix a 523 Origin Is Unreachable

Compare the origin IP address in the Cloudflare DNS settings with the server's real address and correct it if they differ. If the address is right, the hosting provider is the next call: ask whether there is a network or routing incident affecting the server.

Reproduce a 523 response

The fastest way to understand a status code is to trigger one and read the full response. Open the API tester and send a request to https://httpbin.org/status/523 — you will see the 523 status along with every response header the server sent. Comparing those headers against a working request is often what reveals the cause.

That response only imitates the number, which is useful for checking how your own client, alerting or retry logic treats a 523. A real one comes from the software named in the table above, in the circumstances this page describes.

When you are debugging a real endpoint, check the response headers as carefully as the body, and confirm you are using the right HTTP method for the operation.

Related 5xx status codes

500 Internal Server Error

The server hit an unexpected condition and could not complete the request.

501 Not Implemented

The server does not support the functionality required to fulfil the request.

502 Bad Gateway

A server acting as a gateway or proxy received an invalid response from the upstream server.

503 Service Unavailable

The server is temporarily unable to handle the request.

504 Gateway Timeout

A gateway or proxy did not receive a timely response from the upstream server.

505 HTTP Version Not Supported

The server does not support the major HTTP version named in the request.

See also

  • 521 Web Server Is Down — Cloudflare tried to connect to the origin server and the connection was refused.
  • 522 Connection Timed Out — Cloudflare tried to open a TCP connection to the origin server and got no answer in time.
  • DNS lookup — Check which address the origin host name really points to.

References