How to get a File Upload control work with an UpdatePanel

The FileUpload control does not work with asynchronous post backs and therefore does not work from within an AJAX UpdatePanel.

The trick to make the FileUpload to work within an Ajax UpdatePanel is to setup a PostBackTrigger in the UpdatePanel control.

This issue I faced in my one of application ipromotedigital

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<Triggers >
<asp:PostBackTrigger ControlID ="Button1" />
</Triggers>
<ContentTemplate >
<asp:FileUpload ID ="fileupload1" runat ="server" /><br />     
<asp:Button ID ="Button1" runat ="server" Text ="Upload" OnClick="Button1_Click" /><br />
<asp:Label ID ="Lable1" runat ="server"  Text =""></asp:Label>
<asp:LinkButton ID ="LinkButton1" runat="server" Text ="Click Here" OnClick="LinkButton1_Click"></asp:LinkButton>
</ContentTemplate>
</asp:UpdatePanel>