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527 Railgun Error

Deprecated Cloudflare code for a connection failure between the edge and a Railgun listener.

Status

HTTP/1.1 527 Railgun Error

Details

  • Category: 5xx
  • Status: Unofficial (Cloudflare). Not registered with IANA. A server, framework, or CDN convention.
  • Specification: none, not defined by any RFC
  • Cacheable: Not cacheable
  • Response body: Allowed
  • Retry: Retry after a delay

527 indicated that the connection between Cloudflare and a Railgun listener at the origin was interrupted. Railgun was a WAN optimization product that has since been retired, replaced by Argo Smart Routing.

You will only see it in historical logs from sites that ran Railgun.

Common causes

  • The Railgun listener was down or unreachable from the edge.
  • A network interruption between the edge and the listener.

How to fix it

As the client

  • Retry. The condition is entirely on the edge to origin path.

As the server

  • Migrate off Railgun, which is retired, to the current smart routing product.

Examples

A Railgun listener that dropped out

HTTP response

HTTP/1.1 527
Server: cloudflare

See also