Code 525

SSL handshake failed Cloudflare

This error indicates that the SSL handshake between Cloudflare and the website behind it has occurred. This means that Cloudflare is set to use Full SSL in the Cloudflare settings for the domain, so Cloudflare attempts to make a connection using SSL (for requests beginning in https://) to the web server that hosts the domain.

The most common causes include:

  • The website does not have a valid SSL certificate installed
  • The website is not listening on port 443
  • The website does not support or is not configured properly to support SNI
  • The cipher suites that Cloudflare uses do not match what the origin accepts
sequenceDiagram participant User participant Cloudflare participant Website Note right of Website: Behind Cloudflare User->>Cloudflare: Initial request Cloudflare->>+Website: Initiates SSL handshake Website -->>+ Cloudflare: SSL handshake fails Cloudflare -->> User: Returns 525 error