Skip to main content
Castov
HTTP/4xx (Client Error)

425 Too Early

The server is unwilling to process a request that might be replayed (TLS 1.3 0-RTT early data).

❓ Why does this happen?

A non-idempotent request was sent as TLS early data and the server refuses it for replay-attack protection.

✅ How to fix it

Retry the request after the TLS handshake completes, or disable 0-RTT for non-idempotent endpoints.

Return or handle 425 in your stack

// app/api/resource/route.ts
export function GET() {
  return Response.json(
    { error: "Too Early", status: 425 },
    {
      status: 425
    }
  );
}

Live 425 mock endpoint

Point your app, tests, or retry logic at this free public URL to reproduce a real 425 response (CORS enabled, optional ?delay=ms up to 5000).

https://castov.com/api/mock/425

Frequently Asked Questions

What does HTTP Status 425 mean?
The server is unwilling to process a request that might be replayed (TLS 1.3 0-RTT early data).
Why am I getting a 425 status code?
A non-idempotent request was sent as TLS early data and the server refuses it for replay-attack protection.
How do I fix a 425 Too Early error?
Retry the request after the TLS handshake completes, or disable 0-RTT for non-idempotent endpoints.
How can I test how my app handles a 425 response?
Send a request to https://castov.com/api/mock/425 — it returns a real 425 Too Early response with CORS enabled. Add ?delay=2000 to simulate a slow server.

Other 4xx status codes

400401402403404405406407408409410411412413414415416417418421422423425426428429431451499

Browse the full HTTP status codes directory or troubleshoot terminal errors in the Error Fix Encyclopedia.