HTTP Status Code 464 – Incompatible Protocol

The HTTP status code 464 Incompatible Protocol is a non-standard status code used to indicate that a request was made using a protocol version that is not supported by the server. This status code is often used in environments where specific versions of protocols are required for communication, and the server is unable to process requests that do not adhere to these requirements.

Examples

Example 1: Incompatible HTTP Version

In this example, a client attempts to connect to a server using HTTP/2, but the server only supports HTTP/1.1. The server responds with a 464 status code to indicate the protocol incompatibility.

    Client Request:
    GET /api/data HTTP/2
    Host: example.com

    Server Response:
    HTTP/1.1 464 Incompatible Protocol
    Content-Type: text/plain
    Content-Length: 45

    Your request uses an unsupported protocol version.
    

Example 2: WebSocket Protocol Mismatch

In this scenario, a client tries to establish a WebSocket connection using an old protocol version. The server expects WebSocket version 13, but the client uses an outdated version. The server responds with a 464 status code to signal the mismatch.

    Client Request:
    GET /chat HTTP/1.1
    Host: example.com
    Upgrade: websocket
    Connection: Upgrade
    Sec-WebSocket-Version: 8

    Server Response:
    HTTP/1.1 464 Incompatible Protocol
    Content-Type: text/plain
    Content-Length: 59

    Unsupported WebSocket version. Please use version 13 or newer.
    

Example 3 Scenario

# Client sends a request example.
GET /example HTTP/1.1
Host: www.example.com

# Server Response
HTTP/1.1 464 464 Incompatible Protocol
Date: Wed, 09 Oct 2024 23:08:54 GMT
Server: ExampleServer/1.0
Content-Type: application/json

{
    "error": "Description of the error for 464"
}

Example 4 Scenario

# Client sends another example request.
POST /another-example HTTP/1.1
Host: www.example.com

# Server Response
HTTP/1.1 464 464 Incompatible Protocol
Date: Wed, 09 Oct 2024 23:08:54 GMT
Server: ExampleServer/1.0
Content-Type: application/json

{
    "error": "Detailed message for 464"
}

Summary

The 464 Incompatible Protocol status code is a non-standard response indicating that the server cannot process the request due to a protocol version mismatch. This status code is useful in environments where strict protocol adherence is necessary for security or compatibility reasons. By returning a 464 status code, servers can inform clients that they need to update their protocol version to communicate successfully.