“服务器拒绝在没有定义Content-Length头的情况下接受请求。在添加了表明请求消息体长度的有效Content-Length头之后，客户端可以再次提交该请求。“ — wikipedia

“The server refuses to accept the request without a defined Content- Length. 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.“ — ietf