The 411 status code occurs when the server refuses to process a request because the content length was not specified.

Your client did not define the length of the requested content in the request header. The server will not accept the request without a valid Content-Length header field.

The problem can only be resolved by examining what your client system is trying to do then discussing with your ISP why the Web server expects a 'Content-Length' specification. If you are monitor your website through 100pulse, we will intimate whenever you encounter 411 status code error through e-mail or Short message service.