title: jQuery fileupload not working in IE 8 and 9
body: <p><img src="https://i.stack.imgur.com/0xuI2.png" alt="enter image description here"></p>
  
  <p>This code works in FF and chrome. In IE 8 or 9 I get a 500 error saying a not null property is null.</p>
  
  <p>Here is the html</p>
  
  <pre><code>&lt;div id="upload_button_div_general" class="fileupload-buttonbar" data-url="/Upload/SomeMethod"&gt;
      &lt;label class="fileinput-button ui-button ui-widget ui-state-default ui-corner-all ui-button-text-icon-primary" role="button"&gt; 
          &lt;span class="ui-button-text"&gt;
              &lt;span&gt;Add Documents...&lt;/span&gt; 
          &lt;/span&gt;
          &lt;input id="upload_button" type="file" name="postedFiles" multiple="" /&gt;
      &lt;/label&gt;
  &lt;/div&gt;
  &lt;div id="UploadMessage" data-bind="visible: showMessage"&gt; 
      &lt;span&gt;Documents&lt;/span&gt;
  
      &lt;ul data-bind="foreach: upload()"&gt;
          &lt;li&gt; 
              &lt;a href="#" data-bind="click: $parent.openFile"&gt;
                  &lt;span data-bind="text: $data.fileName"&gt;  &lt;/span&gt;
              &lt;/a&gt;
          &lt;/li&gt;
      &lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Here is the javascript</p>
  
  <pre><code>function Upload(div, additionalParams, successFunc, failureFunc) {
      $('#' + div).fileupload({
          dataType: 'json',
          url: rootPath + 'Upload/SomeMethod',
          formData: additionalParams,
          start: function (e, data) {
              showLoading();
          },
          stop: function (e, data) {
              hideLoading();
          },
          add: function (e, data) {
              data.submit();
          },
          always: function (e, data) {
              var result = data.result;
              if (result.HasError) {
                  failureFunc(result.Error);
              } else {
                  successFunc(result);
              }
          }
      });
  };
  </code></pre>
  
  <p>The controller method is</p>
  
  <pre><code>public virtual JsonResult SomeMethod(IEnumerable&lt;HttpPostedFileBase&gt; postedFiles, int id)
  </code></pre>