Element (control) is not a known element.

Question

_{Wednesday, September 28, 2011 7:28 PM}

When I try this simple example, I get this error Element Label1 is not a known element.

<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>

<asp:UpdatePanel ID="UpdatePanel1" runat="server">

<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>

</asp:UpdatePanel>

This is in Visual Studio 2008 and ASP.Net 3.5.  I have found many references but nothing seems to work.  I have added this to the config file. 

<add tagPrefix="ajax" assembly="AjaxControlToolkit" namespace="Ajax Extensions"/>

Nothing works.  Any ideas?

Thanks,

Thor

All replies (3)

_{Friday, September 30, 2011 10:26 AM ✅Answered}

Do it this way

  <asp:UpdatePanel ID="UpdatePanel1" runat="server" ChildrenAsTriggers="false" RenderMode="Block"
                                UpdateMode="Conditional">
                                <ContentTemplate>
                                    <asp:UpdateProgress ID="UpdateProgress1" runat="server">
                                        <ProgressTemplate>
                                            <div class="loading">
                                                <div class="loadmsg">
                                                    Loading data. Please wait..
                                                </div>
                                            </div>
                                        </ProgressTemplate>
                                    </asp:UpdateProgress>

<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>

 </ContentTemplate>
                             
                            </asp:UpdatePanel>

_{Wednesday, September 28, 2011 11:25 PM}

Hi, Please refer this

http://stackoverflow.com/questions/3550589/element-x-is-not-a-known-element-web-application

http://stackoverflow.com/questions/492027/solution-for-element-element-is-not-a-known-element-warning-in-vs2008-when-usi

_{Friday, September 30, 2011 9:02 AM}

I appreciate your help.  I tried the suggestions with no luck.  Actually, I had already tried them.

Thank  you for trying,

Carthalion