Element ScriptManager is not a known element

Discussion in 'ASP .Net' started by John Kotuby, Jan 21, 2009.

  1. John Kotuby

    John Kotuby Guest

    Hi all,

    Just in case anyone gets this error and can't find the solution to their
    problem by Googling it, here is what I discovered in my Web Project. I have
    a rather large project that was started with VS2003 which I continually add
    to and update. Very often if I need a new User Control that resembles an
    existing one I will make a copy of it and then modify. Maybe that's a bad
    practice...maybe not.

    Anyway, I was getting "warning" errors in VS2008 (with the latest service
    packs for it and .NET 3.5) that <asp:ScriptManager> is not a known element.
    I searched the web and scoured my web.config. What I finally discovered was
    that there were old references to System.Web.Extensions at the top of some
    pages, like the one below.

    <%@ Register Assembly="System.Web.Extensions, Version=1.0.61025.0,
    Culture=neutral, PublicKeyToken=31bf3856ad364e35" Namespace="System.Web.UI"
    TagPrefix="asp" %>

    By removing those @Register entries from the page the warnings disappeared
    and intellisense began showing me the ScriptManager as being available. Of
    course I already had a reference to that Asssembly in my web.config, and
    that is probably why my project compiled.
     
    John Kotuby, Jan 21, 2009
    #1
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  2. Here is my take on what you are seeing:

    You started your app with the AJAX controls prior to Visual Studio 2008,
    which you downloaded from www.asp.net. You then updated the website at some
    time for AJAX that ships with VS 2008. When the site was built, the
    registering of System.Web.Extensions was not placed in the web.config, so it
    was registered on each page that used AJAX controls. But, when you updated
    to .NET 3.5 in VS 2008, it added the line to the web.config file.

    This is a common issue for sites that were started with the download AJAX
    extensions for .NET 2.0. The conflict comes from this line in the web.config
    (under <assemblies>):

    <add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral,
    PublicKeyToken=31BF3856AD364E35"/>


    --
    Gregory A. Beamer
    MVP; MCP: +I, Se, SD, DBA

    Blog:
    http://feeds.feedburner.com/GregoryBeamer

    *************************************************
    | Think outside the box! |
    *************************************************
    "John Kotuby" <> wrote in message
    news:emi$...
    > Hi all,
    >
    > Just in case anyone gets this error and can't find the solution to their
    > problem by Googling it, here is what I discovered in my Web Project. I
    > have a rather large project that was started with VS2003 which I
    > continually add to and update. Very often if I need a new User Control
    > that resembles an existing one I will make a copy of it and then modify.
    > Maybe that's a bad practice...maybe not.
    >
    > Anyway, I was getting "warning" errors in VS2008 (with the latest service
    > packs for it and .NET 3.5) that <asp:ScriptManager> is not a known
    > element. I searched the web and scoured my web.config. What I finally
    > discovered was that there were old references to System.Web.Extensions at
    > the top of some pages, like the one below.
    >
    > <%@ Register Assembly="System.Web.Extensions, Version=1.0.61025.0,
    > Culture=neutral, PublicKeyToken=31bf3856ad364e35"
    > Namespace="System.Web.UI" TagPrefix="asp" %>
    >
    > By removing those @Register entries from the page the warnings disappeared
    > and intellisense began showing me the ScriptManager as being available. Of
    > course I already had a reference to that Asssembly in my web.config, and
    > that is probably why my project compiled.
    >
     
    Cowboy \(Gregory A. Beamer\), Jan 22, 2009
    #2
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  3. John Kotuby

    shijobaby

    Joined:
    Dec 15, 2009
    Messages:
    7
    make sure ajax is installed
     
    shijobaby, Sep 9, 2010
    #3
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