title: IE jquery async file upload request pending
body: <p>I have created a new multiple drag drop file upload control with progress bar. It works great with all browsers, except an issue with IE 10 and above.</p>
  
  <p>When I upload files in IE, most of times jquery async request will not complete. It shows pending. I can see it is pending in IE network debugger window. But in all other browsers it work well. I am clueless what is wrong here. Initally I thought it might be something related to caching. But after adding below parameters on server response. It still goes in pending state</p>
  
  <pre><code>context.Response.AppendHeader("Cache-Control", "no-cache"); // HTTP 1.1
  context.Response.AppendHeader("Pragma", "no-cache"); // HTTP 1.1 
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/BiUNM.png" alt="enter image description here">
  <img src="https://i.stack.imgur.com/yRipT.png" alt="enter image description here">
  <img src="https://i.stack.imgur.com/UcP7z.png" alt="enter image description here"></p>
  
  <pre><code>for (var i = 0; i &lt; files.length; i++) {
          var data = new FormData();
          data.append(files[i].name, files[i]);
          uploadFile(handlerurl, data);
      }
  function uploadFile(handlerurl, formData) {
                  var jqXHR = $.ajax({
                      type: 'POST',
                      url: handlerurl,
                      contentType: false,
                      processData: false,
                      async: true,
                      cache: false,
                      data: formData,                         
                      xhr: function () {   },
                      success: function (result, status, xhr) {   },
                      error: function (xhr, status, error) {   }
            });
  }
  </code></pre>
  
  <p>I am calling this function per file. I am not sure what is wrong with IE.</p>
  
  <p>Edit : After debugging, found out that server breakpoint will hit. but there is no files in <strong>context.Request.Files</strong>. No files send from jquery/AJAX.
  You can reproduce this issue by keep upload same file again and again.</p>