title: FileUploader.Has File always returning false in .net 4.0
body: <p>i have been working trying to find the answers for this but i cant find any solutions that worked. </p>
  
  <pre><code>MultipleFileUploader.ascx:
       &lt;asp:ScriptManagerProxy ID="ScriptManagerProxy1" runat="server"&gt;
          &lt;/asp:ScriptManagerProxy&gt;  
      &lt;asp:UpdatePanel ID="UpdatePanel1"  runat="server"&gt;
          &lt;ContentTemplate&gt;
      &lt;asp:FileUpload ID="FileUpload1" runat="server" 
                      multiple="multiple" onchange="__doPostBack('&lt;%= UpdatePanel1.ClientID %&gt;', ''); type="file" /&gt;
        &lt;/ContentTemplate&gt;
      &lt;/asp:UpdatePanel&gt;
  </code></pre>
  
  <p>Behind Codes: </p>
  
  <pre><code> protected void Page_Load(object sender, EventArgs e)
      {
          if (FileUpload1.HasFile)
              onAttach();
      }
  </code></pre>
  
  <p>It uploads the file the moment the user selects a file with the Postback __doPostBack
  It shouldnt be browser issue because im getting the same problem on chrome firefox and IE. 
  The codes has always been working fine till we upgraded to .net 4.0, for some reason it FileUploader.HasFile always return false. </p>
  
  <p>I have tried: </p>
  
  <pre><code>Page.Form.Attributes.Add("enctype", "multipart/form-data"); 
  </code></pre>
  
  <p>and : </p>
  
  <pre><code>&lt;Triggers&gt; 
     &lt;asp:PostBackTrigger ControlID="btnUploadFile" /&gt; 
  &lt;/Triggers&gt; 
  </code></pre>
  
  <p>Am i missing something simple or anything? 
  Any help rendered is very much appreciated. 
  Many Thanks.</p>