426 Upgrade Required
426 Upgrade Required 是一种 HTTP 协议的错误状态代码，表示服务器拒绝处理客户端使用当前协议发送的请求，但是可以接受其使用升级后的协议发送的请求。
服务器会在响应中使用 Upgrade 首部来指定要求的协议。
状态
426 Upgrade Required
示例
HTTP/1.1 426 Upgrade Required Upgrade: HTTP/3.0 Connection: Upgrade Content-Length: 53 Content-Type: text/plain This service requires use of the HTTP/3.0 protocol
规范
| Specification |
|---|
| HTTP Semantics # status.426 |