411Length Required

由于缺少确定的 Content-Length 首部字段，服务器拒绝客户端的请求。

The server refuses to accept the request without a defined Content-Length¹.

The client MAY repeat the request if it adds a valid Content-Length header field containing the length of the message body in the request message.

• ¹ Content-Length RFC7230 Section 3.3.2
• Source: RFC7231 Section 6.5.10