Last Updated: 20 May 2022 09:49 by ADMIN
Release R1 2022
Created on: 17 Nov 2021 14:50
Category: Calendar
Type: Feature Request
Javascript error in R3 2021 SP1 caused by DatePicker with Classic render mode and EnableKeyboardNavigation=true

Error message:

Uncaught TypeError: Cannot read properties of undefined (reading '_events')
    at Sys.UI.DomEvent.addHandler (Telerik.Web.UI.WebResource.axd:6:57366)
    at Telerik.Web.UI.RadCalendar.initialize (Telerik.Web.UI.WebResource.axd:4916:8)
    at Telerik.Web.UI.RadCalendar.endUpdate (Telerik.Web.UI.WebResource.axd:6:53689)
    at Sys.Component.create (Telerik.Web.UI.WebResource.axd:6:55151)
    at Array.<anonymous> (Default.aspx:130:5)
    at Telerik.Web.UI.WebResource.axd:6:51370
    at Sys._Application._raiseInit (Telerik.Web.UI.WebResource.axd:6:72276)
    at Sys._Application.initialize (Telerik.Web.UI.WebResource.axd:6:69772)
    at b (Telerik.Web.UI.WebResource.axd:6:71512)
    at HTMLDocument.a (Telerik.Web.UI.WebResource.axd:6:71786)

Possible workarounds from Admin: 

1) Use Lightweight render mode instead of Classic: 

2) Disable temporarily the keyboard navigation of the control

3) Use the attached script and load it on the page: 

3.1) Using a RadScriptManager (adjust the file name and path to fit your application)

<telerik:RadScriptManager ID="RadScriptManager1" runat="server">
        <telerik:RadScriptReference Path="fix.js" OutputPosition="End" />


3.2) In an inline script tag somewhere AFTER the ScriptManager(e.g. at the end of the <form> or <body> tag)

3.3) As a script reference - place it AFTER the script manager as 3.2) or use the defer="defer" attribute

<script defer="defer" src="fix.js"></script>


4) Submit a support ticket if you would prefer a custom Telerik.Web.UI.dll assembly with the issue resolved.



Posted on: 20 May 2022 09:49

Hi Vinay,

The bug discussed in this thread is fixed in our R1 2022 release, so you will need to upgrade to it (or to a later version of the controls) in order to have the fix in your application:

You can download a fixed version of the controls from the Download section of your Telerik account here (you can change the version from the Version dropdown):

Progress Telerik

Love the Telerik and Kendo UI products and believe more people should try them? Invite a fellow developer to become a Progress customer and each of you can get a $50 Amazon gift voucher.

Posted on: 19 May 2022 21:32
How can I get Telerik.Web.UI.dll assembly with the issue resolved ?