HTTP 425 Too Early vs 505 HTTP Version Not Supported
HTTP 425 (Too Early) is a 4xx Client Error response, while 505 (HTTP Version Not Supported) is a 5xx Server Error response. 425 indicates that the server is unwilling to risk processing a request that might be replayed. Used with TLS 1.3 early data (0-RTT). In contrast, 505 means that the server does not support the HTTP version used in the request.
Description
The server is unwilling to risk processing a request that might be replayed. Used with TLS 1.3 early data (0-RTT).
When You See It
When a server rejects a request sent as TLS 1.3 early data due to replay risk.
How to Fix
Retry the request after the TLS handshake completes.
Description
The server does not support the HTTP version used in the request.
When You See It
When a client uses an HTTP version the server doesn't support.
How to Fix
Use a supported HTTP version (typically HTTP/1.1 or HTTP/2).
Key Differences
425 is a 4xx Client Error response, while 505 is a 5xx Server Error response.
HTTP 425: The server is unwilling to risk processing a request that might be replayed. Used with TLS 1.3 early data (0-RTT).
HTTP 505: The server does not support the HTTP version used in the request.
You encounter 425 when when a server rejects a request sent as TLS 1.3 early data due to replay risk.
You encounter 505 when when a client uses an HTTP version the server doesn't support.
When to Use Which
For 425 (Too Early): Retry the request after the TLS handshake completes. For 505 (HTTP Version Not Supported): Use a supported HTTP version (typically HTTP/1.1 or HTTP/2).