4×× Client Error
425 Too Early
The server is unwilling to risk processing a request that might be replayed.
User agents that send a request in early data are expected to retry the request when receiving a 425 (Too Early) response status code. A user agent SHOULD retry automatically, but any retries MUST NOT be sent in early data.
In all cases, an intermediary can forward a 425 (Too Early) status code. Intermediaries MUST forward a 425 (Too Early) status code if the request that it received and forwarded contained an Early-Data header field. Otherwise, an intermediary that receives a request in early data MAY automatically retry that request in response to a 425 (Too Early) status code, but it MUST wait for the TLS handshake to complete on the connection where it received the request.
The server cannot assume that a client is able to retry a request unless the request is received in early data or the Early-Data header field is set to "1". A server SHOULD NOT emit the 425 status code unless one of these conditions is met.
The 425 (Too Early) status code is not cacheable by default. Its payload is not the representation of any identified resource.
- Source: RFC4918 Section 5.2
425 Code References
.NET HTTP Status Enum
Rust HTTP Status Constant
Rails HTTP Status Symbol
Go HTTP Status Constant
Symfony HTTP Status Constant
Python HTTP Status Constant