Handler was not added through the Sys.UI.DomEvent.addHandler method. (a solution) RRS feed

  • Question

  • User-1644933537 posted

    The following is a solution to the above error I encountered. Hopefully I can save others with a similar problem from endless hours of sifting through unhelpful answers.

    I searched and searched and only found suggestions that recommended I do the following.

    1. Change the ToolkitScriptManager ScriptMode from "Debug" to "Release"

    2. In web.config change <compilation debug="true" targetFramework="4.0"> to <compilation debug="false" targetFramework="4.0">

    Neither suggestion worked for me, either separately or combined.


    I had a GridView (simplified)

    <asp:Panel ID="Panel_GridView_Data" runat="server">
    	<asp:UpdatePanel ID="UpdatePanel_GridView_Data" runat="server" UpdateMode="Conditional">
    			<asp:GridView ID="GridView_Data">
    						<uc:GridView_Details runat="server" ID="UserControl_GridViewDetails" />

    In the UserControl (simplified)

    <asp:LinkButton ID="LinkButton_GridView_DataDetailId" runat="server" Text='<%# Eval("SomeId") %>' />
    <asp:ModalPopupExtender ID="ModalPopupExtender_GridView_DataDetails" runat="server" 
    <asp:Panel ID="Panel_DataDetails" runat="server" style="display:none" >
    	<asp:UpdatePanel ID="UpdatePanel_Details" runat="server" UpdateMode="Conditional">
    			<asp:FormView ID="FormView_BroachDetails" runat="server">
    			<asp:Button ID="ModalPopupExtender_GridView_DataDetails_Close" runat="server" Text="Close"


    Originally I didn't have the ModalPopupExtender_GridView_DataDetails_Close control because I was using the CancelControlID of the ModalPopupExtender to close the Panel.

    Problem arose when I entered into Edit mode in the FormView. Upon save or cancel the 'Close' button for the Modal would not work, no error, just wouldn't close. I looked back at the page I copied the structure from and saw that I had added a OnClick event to the Button control and thus closed the Panel from code, so I did the same here.

    When I added the OnClick event I didn't remove the CancelControlID property from the ModalPopupExtender. This oversight was causing the 'Sys.UI.DomEvent.addHandler' error.

    Finally after hours of fruitless searching I returned to the html and reviewed the page attempting to find differences in the two pages. Somehow I noticed the aforementioned CancelControlID (I would have expected myself to overlooked that).

    I promptly removed it and the error stopped.

    Thursday, March 13, 2014 1:01 PM


  • User-1644933537 posted

    See solution in the initial post

    • Marked as answer by Anonymous Thursday, October 7, 2021 12:00 AM
    Thursday, March 13, 2014 1:04 PM