HTTP/5xx (Server Error)
525 SSL Handshake Failed
Cloudflare-specific: the SSL/TLS handshake between Cloudflare and the origin failed.
❓ Why does this happen?
Origin has no valid certificate on port 443, or cipher/SNI mismatch in Full / Full (strict) SSL mode.
✅ How to fix it
Install a valid certificate (or a Cloudflare Origin CA certificate) on the origin and ensure port 443 serves TLS.
Return or handle 525 in your stack
// Note: 525 is normally generated by Cloudflare, not your app.
// Emitting it yourself is only useful for testing client error handling.
// app/api/resource/route.ts
export function GET() {
return Response.json(
{ error: "SSL Handshake Failed", status: 525 },
{
status: 525
}
);
}Live 525 mock endpoint
Point your app, tests, or retry logic at this free public URL to reproduce a real 525 response (CORS enabled, optional ?delay=ms up to 5000).
https://castov.com/api/mock/525Frequently Asked Questions
What does HTTP Status 525 mean?
Why am I getting a 525 status code?
How do I fix a 525 SSL Handshake Failed error?
How can I test how my app handles a 525 response?
Other 5xx status codes
Browse the full HTTP status codes directory or troubleshoot terminal errors in the Error Fix Encyclopedia.