What is a 1013 Error?

A 1013 HTTP hostname and TLS SNI hostname mismatch error is a Cloudflare-specific error code for: "The website domain in your web request didn't match the SSL encryption handshake name.".

How do I fix or troubleshoot a 1013 Error?

Common steps include reloading the page in your browser, checking for typos in the URL, verifying server status, clearing browser cache or cookies, and contacting the website owner or server administrator if the error persists.

1013 Error | Error-Message.Net

Common cause

The Server Name Indication (SNI) hostname sent by the client during the TLS handshake does not match the Host header sent in the subsequent HTTP request.

Cloudflare enforces SNI matching to prevent SSL spoofing and cross-tenant proxy abuse.

Resolution:

If you are a visitor:

Clear your browser cache and SSL state, or update your browser software.
If using custom proxy software or VPN tunnels, ensure they do not alter HTTP Host headers independently of TLS SNI handshakes.

If you are a developer:

When using command-line tools like curl, ensure your request URL matches the SNI name (e.g. curl --resolve example.com:443:104.16.x.x https://example.com).

Source: Cloudflare Documentation - Troubleshooting Cloudflare 1XXX errors (Error 1013)