← All status codes4xx – Client Error

HTTP 464 – Incompatible Protocol Versions

(AWS ELB) The client and the registered target are using incompatible protocol versions, so the request cannot be forwarded.

Common use case

Logged when, for example, an HTTP/2-only client talks to a target group that only supports HTTP/1.1, or vice versa, and the load balancer can't bridge the gap.

History

An AWS-specific extension for ELB/ALB access logs.

Did you know?

It typically points to a target-group configuration mismatch rather than anything wrong with the request itself.

Other 4xx codes

400Bad Request401Unauthorized402Payment Required403Forbidden404Not Found405Method Not Allowed406Not Acceptable407Proxy Authentication Required408Request Timeout409Conflict410Gone411Length Required412Precondition Failed413Content Too Large414URI Too Long415Unsupported Media Type416Range Not Satisfiable417Expectation Failed418I'm a teapot422Unprocessable Content425Too Early426Upgrade Required428Precondition Required429Too Many Requests430Shopify Security Rejection431Request Header Fields Too Large444No Response451Unavailable For Legal Reasons460Client Closed Connection463Malformed X-Forwarded-For Header494Request Header Too Large495SSL Certificate Error496SSL Certificate Required497HTTP Request Sent To HTTPS Port499Client Closed Request