Error 527
Error 527 Railgun Listener to Origin Error Error
What This Error Means
Error 527 indicates an interrupted connection between Cloudflare and the origin's Railgun server (rg-listener). Railgun is a WAN optimization technology.
Common Causes
- Firewall interference between the Railgun listener and the origin web server.
- Railgun listener is not running or misconfigured.
- Network timeout between Cloudflare and the Railgun listener.
How to Fix It (For Users)
- 1 This is a server infrastructure issue.
For Site Owners / Developers
- Check that the Railgun listener is active.
- Ensure port 2408 is open and allowed.
- Review Railgun logs for timeout or connection errors.
When It Is NOT Your Fault
If the Railgun service crashes.
Check if this outage affects everyone globally
This error often indicates a wider problem. Use our tool to verify if the site is down for everyone.
Check Website Status →Recommended Tool to Prevent This Error
Fix DNS resolution issues and protect your site from DDoS attacks with Cloudflare.