Telerik UI for ASP.NET AJAX and AJAX Control Toolkit

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  1. Telerik Admin
    Telerik Admin avatar
    1679 posts
    Member since:
    Oct 2004

    Posted 16 Apr 2014 Link to this post

    AjaxControlToolkit Version 15.1 (March 2015)

    The 15.1 AjaxControlToolkit release causes an error when Telerik UI for ASP.NET AJAX controls are used together with AjaxControlToolkit controls: "this._setProperties is undefined".

    The error stems from the AjaxControlToolkit scripts and Telerik has no control over it. For the time being, there is no possible workaround from our end.

    The previous workaround (using the ToolkitScriptManager) is no longer applicable, because the ToolkitScriptManager has been removed.

    Ideas we can suggest are:

    • Remove the AjaxControlToolkit from your project and use Telerik UI for ASP.NET AJAX controls instead.
    • Contact the developers of the AjaxControlToolkit bundle so they can fix the issue.


    AjaxControlToolkit Version 7.1005 (September 2013)

    Recently, the AJAX Toolkit Team announced that standard script manager can no longer be used with their controls.
    “- You must use the ToolkitScriptManager instead of the ScriptManager with the Ajax Control Toolkit.”

    Since the RadScriptManager is based on the standard asp:ScriptManager, this change makes it not compatible, too. Therefore, to use both of the Telerik UI and AJAX Toolkit control bundles simultaneously within the same project, you have to use the ToolkitScriptManager.

    Upon using the toolkit manager, you can come across an error when using an UpdatePanel. We’ve found out that this is due to the ToolkitScriptManager having a bug with script combining. The bug is fixed one day after their latest release:

    The problem can be reproduced in release mode when scripts are combined and after an AJAX request. The temporary workaround is to set CombineScripts to false:

    <asp:ToolkitScriptManager runat="server" ID="ScriptManager1" CombineScripts="false"   />

    Please note that the issue is not reproducible into debug mode, because the script combining logic works only in release mode.
  2. Kavita
    Kavita avatar
    3 posts
    Member since:
    Mar 2014

    Posted 29 Sep 2014 Link to this post


    We were using Telerik Controls for our 3.4 project
    till this and now when we decided to upgrade to 4.5 we had to upgrade
    to Telerik latest controls and so I did.

    I downloaded Telerik v 2014.2.724.45,I also using
    AjaxcontrolToolkit v4.0.30319 and now If I Start running project for
    4.5 I see the below error on each page.


    0x800a138f - JavaScript runtime error: Unable to get property
    'UI' of undefined or null reference


    I read few things related to this which mentions not to use
    TelerikRadscriptManager Is that the case causing this error ? Any more details
    would be appreciated.


    Thanks & Regards,

    Kavita Tengse.

    Developer (

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  4. Eyup
    Eyup avatar
    2941 posts

    Posted 30 Sep 2014 Link to this post

    Hi Kavita,

    Thank you for contacting us.

    I would suggest that you open an official support ticket to provide a very basic runnable sample to demonstrate the issue and elaborate on your specific scenario. You can post your technical queries in our support ticketing system or our regular forums since sticky threads are for more like breaking information notice:

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