Updateprogessbar is not working when Setting AssociatedUpdatePanelID?

I have two updatepanel and a progressbar on the page. If I set the AssociatedUpdatePanelID, then progressbar is not working, without setting AssociatedUpdatePanelID progress bar is working but the problem is working for both updatepanel. But I need to work on one updatepanel.

 <asp:Button ID="Button1" runat="server" Text="Button1" OnClick="Button1_Click" />
    <asp:Button ID="Button2" runat="server" Text="Button2" OnClick="Button2_Click" />
    <asp:UpdateProgress runat="server" ID="prg" AssociatedUpdatePanelID="upnl">
        <ProgressTemplate>
            <img src="Images/progressbar.gif" />
        </ProgressTemplate>
    </asp:UpdateProgress>
    <br />
    <asp:UpdatePanel runat="server" ID="upnl" UpdateMode="Conditional">
        <ContentTemplate>
        </ContentTemplate>
        <Triggers>
            <asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" />
        </Triggers>
    </asp:UpdatePanel>
    <asp:UpdatePanel runat="server" ID="upnl1" UpdateMode="Conditional">
        <ContentTemplate>
        </ContentTemplate>
        <Triggers>
            <asp:AsyncPostBackTrigger ControlID="Button2" EventName="Click" />
        </Triggers>
    </asp:UpdatePanel>

Code Behind – C#

protected void Button1_Click(object sender, EventArgs e)
{
    System.Threading.Thread.Sleep(3000);
}
protected void Button2_Click(object sender, EventArgs e)
{
    System.Threading.Thread.Sleep(3000);
}

In this video, he also not set AssociatedUpdatePanelID
http://www.asp.net/learn/ajax-videos/video-123.aspx

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

Excellant Article: Explaining every thing in very simple manner……….
http://www.codedigest.com/Articles/ASPNETAJAX/125_Using_UpdateProgress_Control_Effectively.aspx

By Design External triggers for an UpdatePanel do not fire an associated UpdateProgress, since the implementation of enabling the UpdateProgress control searches the control hierarchy for the calling control; an external trigger will not be present in the control hierarchy.

Method 2

AssociatedUpdatePanelID property in the UpdateProgress control will not work if the event that triggered the UpdatePanel is also external.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0