jQuery ajax XML Http Request not works

This could be happening if your ajax request is getting canceled before it completes. jQuery throws the error event when the user navigates away from the page either by refreshing, clicking a link, or changing the URL in the browser. You can detect these types of errors by by implementing an error handler for the ajax call, and inspecting the xmlHttpRequest object:

$.ajax({
    /* ajax options omitted */
    error: function (xmlHttpRequest, textStatus, errorThrown) {
         if(xmlHttpRequest.readyState == 0 || xmlHttpRequest.status == 0) 
              return;  // it's not really an error
         else
              // Do normal error handling
});