HTTP 527 — Railgun Error
HTTP 527
Railgun Error
A retired Cloudflare error about a failed connection to a Railgun listener.
What 527 actually means
Cloudflare-specific and now obsolete. Railgun was Cloudflare's WAN optimisation product, which put a listener at the origin to compress traffic between it and the edge; a 527 meant the edge could not reach that listener. Railgun has been deprecated and retired, so this code should no longer appear on current configurations. Seeing one means something is still pointing at legacy infrastructure.
Common causes
- A legacy Railgun listener unreachable or stopped
- A stale configuration still referencing Railgun after its retirement
- A firewall blocking the Railgun listener port
If you're just trying to view the page
- Nothing — the site is using retired infrastructure
- Report it to the site owner with the Ray ID
If it's your site
- Remove any remaining Railgun configuration; the product has been retired
- Use Cloudflare Argo Smart Routing or a Cloudflare Tunnel for the same class of benefit
Reference
- Status code
- 527
- Reason phrase
- Railgun Error
- Category
- 5xx — Server Error
- Cacheable by default
- No
Common questions
- What does HTTP 527 mean?
- A retired Cloudflare error about a failed connection to a Railgun listener. Cloudflare-specific and now obsolete. Railgun was Cloudflare's WAN optimisation product, which put a listener at the origin to compress traffic between it and the edge; a 527 meant the edge could not reach that listener.
- How do I fix a 527 error?
- Nothing — the site is using retired infrastructure
- Is 527 a client error or a server error?
- 527 is in the 5xx range, which means server error. The request was acceptable but the server could not fulfil it, so retrying later can succeed.
Related pages
- 500 Internal Server Error Something went wrong on the server and it has no more specific code to describe
- 502 Bad Gateway A proxy or gateway reached the server behind it and got back a broken response,
- 503 Service Unavailable The server is temporarily unable to handle the request, usually because it is ov
- 504 Gateway Timeout A proxy or gateway waited for the server behind it and gave up before an answer
- 524 A Timeout Occurred Cloudflare connected to the origin successfully but the origin did not finish re
- 521 Web Server Is Down Cloudflare could not connect to the origin server because it refused the connect
- 522 Connection Timed Out Cloudflare tried to open a connection to the origin server and never got a reply
- 520 Web Server Returned an Unknown Error Cloudflare reached the origin server but got back a response it could not make s
- 525 SSL Handshake Failed The TLS handshake between Cloudflare and the origin server failed.
- 526 Invalid SSL Certificate The origin server presented a TLS certificate that Cloudflare could not validate
- 530 Origin DNS Error A Cloudflare error shown alongside a 1xxx error code that carries the real expla
- 501 Not Implemented The server does not support the functionality needed to fulfil the request, usua