What does HTTP 425 mean?
The server is unwilling to risk processing a request that might be replayed.
Common causes and when you see it
TLS 1.3 early data (0-RTT) requests.
How to fix or handle it
Retry once the TLS handshake is complete.
Test it yourself
Send a request with the online API tester, inspect the response with the HTTP header checker, or host an endpoint that returns 425 with the mock API generator to see how your app reacts.
HTTP 425 questions
The server is unwilling to risk processing a request that might be replayed.
TLS 1.3 early data (0-RTT) requests.
Retry once the TLS handshake is complete.