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Telerik.Web.UI.RadTreeView Is null or not an object

Symptoms

RadTreeView Runtime Error

Causes and Solutions

Telerik RadTreeView cannot find its JavaScript code. The necessary code is fetched either from the WebResource.axd file or from files located in the project's folder, depending on the control's settings.

Case 1: EnableEmbeddedScripts property of Telerik RadTreeView is set to false:

  • The control's scripts are not referenced - first, copy the needed script files from the installation directory of RadControls for ASP.NET AJAX in the project's directory; then reference them from the ScriptManager like this:
<asp:ScriptManager ID="ScriptManager1" runat="server">
    <Scripts>
        <asp:ScriptReference Path="~/Scripts/Common/Core.js" />
        <asp:ScriptReference Path="~/Scripts/Common/Animation/AnimationScripts.js" />
        <asp:ScriptReference Path="~/Scripts/Common/Navigation/NavigationScripts.js" />
        <asp:ScriptReference Path="~/Scripts/TreeView/RadTreeViewScripts.js" />
    </Scripts>
</asp:ScriptManager>
  • The control's scripts are referenced but the error still shows which means the RadTreeViewScripts.js file is not physically in the location specified by the Path property or the file is inaccessible.To make sure that this is really the case, you can copy the path to the RadTreeViewScripts.js file for example in the browser and see if you have access to this file. If you cannot retrieve this file you will see the following error message:

Page Not Found

The solution is to make sure that the file is intact, and it is in the location specified by the Path property of the ScriptManager. If the file is accessible you will be able to view it or download it:

RadTreeView Download Script

Case 2: EnableEmbeddedScripts property of Telerik RadTreeView is set to true (Default case)

In this case RadTreeView will search for its JavaScript code embedded in the WebResource.axd and ScriptResource.axd as part of the DLL of the control's suite.

The following articles discuss possible causes and solutions of the problem: