Virtualization is not working for RadMultiSelect

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chandi asked on 26 Jan 2022, 11:54 AM


My main thread is  "Check All" feature is not working as expected with Load On Demand

As there is limitation on LoadOnDemand feature in RadComboBox control, as a workaround I used RadMultiSelect with Virtualization.

But when I add the below line it showing console error.

<VirtualSettings ItemHeight="26" ValueMapper="valueMapper" />

As you requested in main thread I am attaching current implementation to investigate the problem. 

Attaching relevant files for your reference since full project can't upload due to max size exceed.

Highly appreciate your quick response.





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Attila Antal
Telerik team
answered on 27 Jan 2022, 04:25 PM

Hello Chandi,

The error message seen in the screenshot is caused by the missing Scripts.

RadMultiSelect is a Wrapper for the Kendo UI MultiSelect. This is a jQuery widget, therefore, it will require jQuery loaded on the page.

Try including the following Scripts which will setup the jQuery references for the MultiSelect:

<%--<telerik:RadScriptManager runat="server" ID="RadScriptManager1" />--%>

<telerik:RadScriptManager ID="RadScriptManager1" runat="server">
        <asp:ScriptReference Assembly="Telerik.Web.UI" Name="Telerik.Web.UI.Common.Core.js" />
        <asp:ScriptReference Assembly="Telerik.Web.UI" Name="Telerik.Web.UI.Common.jQuery.js" />
        <asp:ScriptReference Assembly="Telerik.Web.UI" Name="Telerik.Web.UI.Common.jQueryInclude.js" />


For more information about jQuery, you can check out the Using jQuery article:


Once you resolve this issue, you can proceed and finish configuring the WebService.


Please let me know if you have any questions.


Attila Antal
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commented on 28 Jan 2022, 02:59 AM

Hi Attila,

Thank you very much for your response.

Yes, it worked fine after added jQuery references.

Thanks again :)

Best Regards,


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