Yes. 5xx codes are server errors: The server failed to fulfil a valid-looking request.

5xx · Server errorNot part of the HTTP standard

HTTP 525 SSL Handshake Failed

Cloudflare: the TLS handshake with the origin failed.

Example response

HTTP

HTTP/1.1 525 SSL Handshake Failed
Content-Type: application/json; charset=utf-8

{ "error": "SSL Handshake Failed" }

Look up the headers shown here in the HTTP headers reference.

What does HTTP 525 mean?: SSL Handshake Failed. Cloudflare: the TLS handshake with the origin failed.
Is 525 an error?: Yes. 5xx codes are server errors: The server failed to fulfil a valid-looking request.