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  • Category: ASP.NET

    Unknown server tag 'cc1:Editor. error

    Am using Editor but am get Unknown server tag ' to solve this.

    My Code :

    <%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit.HTMLEditor" TagPrefix="cc1" %>

    <html xmlns="">
    <head runat="server">
    <form id="form1" runat="server">
    <cc1:Editor ID="Editor1" runat="server" Height="350px" />
    <asp:ScriptManager ID="ScriptManager1" runat="server">
  • #767174
    Please make sure to register the toolkit tag prefix in web.config.
    change TagPrefix to

    < %@ Register TagPrefix="ajaxToolkit" Namespace="AjaxControlToolkit" Assembly="AjaxControlToolkit"%>
    < ajaxToolkit:ToolkitScriptManager ID="ToolkitScriptManager1" runat="Server" />
    < ajaxToolkit:HtmlEditorExtender TargetControlID="txtComments" runat="server" />
    //Check in your web config for AjaxControlToolkit tagPrefix as below
    < configuration>
    < system.web>
    < compilation debug="true" targetFramework="4.0" />
    < pages>
    < controls>
    < add tagPrefix="ajaxToolkit" assembly="AjaxControlToolkit" namespace="AjaxControlToolkit" />
    < /controls>
    < /pages>
    < /system.web>
    < /configuration>

    Editor, DotNetSpider MVM
    Microsoft MVP 2014 [ASP.NET/IIS]

  • #767178
    Add following tag for 'cc1' inside web.config inbetween <system.web> tag so that your code will work fine:

    <add tagPrefix="cc1" assembly="AjaxControlToolkit" namespace="AjaxControlToolkit" />
    < /controls>

  • #767180
    I tried this method but same error i getting. any one support

  • #767184

    There are several reasons behind this issue, first check whether are you able to find the controls using that TagPrefix, if not then that is TagPrefix issue as suggested by above solution you can change the TagPrefix and fix the issue, if you still got the error then check whether in designer are you able to see the AJAX Toolkit registration, if not delete the register and then add it again.

    Give respect to your work, Instead of trying to impress your boss.

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  • #767185
    Request you to please remove all references of AjaxControlToolKit dll from your solution. After that Clean/Rebuid your solution and add those references again. Then add proper web.config tags again and check.
    Also go through any of the control codes given on this site: and make sure you have all the same code placed.

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