title: Error when debugging a page using Ajax Toolkit
body: <p>I'm getting this error </p>
  
  <blockquote>
    <p>Could not load type
    'System.Web.UI.ScriptReferenceBase'
    from assembly 'System.Web.Extensions,
    Version=3.5.0.0, Culture=neutral,
    PublicKeyToken=31bf3856ad364e35'</p>
  </blockquote>
  
  <p>Procedure I applied for downloading :</p>
  
  <ol>
  <li><p>I have downloaded file  "AjaxControlToolkit.Binary.NET35.zip" from <a href="http://ajaxcontroltoolkit.codeplex.com/releases/view/63654" rel="nofollow">http://ajaxcontroltoolkit.codeplex.com/releases/view/63654</a></p></li>
  <li><p>Installed as instructed here <a href="http://www.asp.net/ajaxlibrary/act.ashx" rel="nofollow">http://www.asp.net/ajaxlibrary/act.ashx</a></p></li>
  </ol>
  
  <p>I am using Visual Studio 2008 and downloaded Ajax version of 3.5</p>
  
  <p>My Default Page </p>
  
  <pre><code>&lt;%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %&gt;
  &lt;%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajaxToolkit" %&gt;
  &lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;
  &lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
  &lt;head runat="server"&gt;
      &lt;title&gt;Untitled Page&lt;/title&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;form id="form1" runat="server"&gt;
      &lt;div&gt;
          &lt;ajaxToolkit:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server" EnableScriptGlobalization="true"
          EnableScriptLocalization="true"&gt;
          &lt;/ajaxToolkit:ToolkitScriptManager&gt;
      &lt;asp:TextBox runat="server" ID="Date1" autocomplete="off" /&gt;&lt;br /&gt;
          &lt;ajaxToolkit:CalendarExtender ID="defaultCalendarExtender" runat="server" TargetControlID="Date1" /&gt;
  
      &lt;/div&gt;
      &lt;/form&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>My web.Config file is</p>
  
  <pre><code>&lt;?xml version="1.0"?&gt;
  &lt;!-- 
      Note: As an alternative to hand editing this file you can use the 
      web admin tool to configure settings for your application. Use
      the Website-&gt;Asp.Net Configuration option in Visual Studio.
      A full list of settings and comments can be found in 
      machine.config.comments usually located in 
      \Windows\Microsoft.Net\Framework\v2.x\Config 
  --&gt;
  &lt;configuration&gt;
      &lt;configSections&gt;
          &lt;sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"&gt;
              &lt;sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"&gt;
                  &lt;section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/&gt;
                  &lt;sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"&gt;
                      &lt;section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="Everywhere"/&gt;
                      &lt;section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/&gt;
                      &lt;section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/&gt;
                      &lt;section name="roleService" type="System.Web.Configuration.ScriptingRoleServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/&gt;
                  &lt;/sectionGroup&gt;
              &lt;/sectionGroup&gt;
          &lt;/sectionGroup&gt;
      &lt;/configSections&gt;
      &lt;appSettings/&gt;
      &lt;connectionStrings/&gt;
      &lt;system.web&gt;
          &lt;!-- 
              Set compilation debug="true" to insert debugging 
              symbols into the compiled page. Because this 
              affects performance, set this value to true only 
              during development.
          --&gt;
          &lt;compilation debug="true"&gt;
              &lt;assemblies&gt;
                  &lt;add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/&gt;
                  &lt;add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
                  &lt;add assembly="System.Data.DataSetExtensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/&gt;
                  &lt;add assembly="System.Xml.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/&gt;
                  &lt;add assembly="System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/&gt;
                  &lt;add assembly="System.Web.Extensions.Design, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
                  &lt;add assembly="System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/&gt;&lt;/assemblies&gt;
              &lt;/compilation&gt;
          &lt;!--
              The &lt;authentication&gt; section enables configuration 
              of the security authentication mode used by 
              ASP.NET to identify an incoming user. 
          --&gt;
          &lt;authentication mode="Windows"/&gt;
          &lt;!--
              The &lt;customErrors&gt; section enables configuration 
              of what to do if/when an unhandled error occurs 
              during the execution of a request. Specifically, 
              it enables developers to configure html error pages 
              to be displayed in place of a error stack trace.
  
          &lt;customErrors mode="RemoteOnly" defaultRedirect="GenericErrorPage.htm"&gt;
              &lt;error statusCode="403" redirect="NoAccess.htm" /&gt;
              &lt;error statusCode="404" redirect="FileNotFound.htm" /&gt;
          &lt;/customErrors&gt;
          --&gt;
          &lt;pages&gt;
              &lt;controls&gt;
                  &lt;add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
                  &lt;add tagPrefix="asp" namespace="System.Web.UI.WebControls" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
          &lt;!--&lt;add namespace="AjaxControlToolkit" assembly="AjaxControlToolkit" tagPrefix="ajaxToolkit"/&gt;--&gt;
        &lt;/controls&gt;
          &lt;/pages&gt;
          &lt;httpHandlers&gt;
              &lt;remove verb="*" path="*.asmx"/&gt;
              &lt;add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
              &lt;add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
              &lt;add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false"/&gt;
          &lt;/httpHandlers&gt;
          &lt;httpModules&gt;
              &lt;add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
          &lt;/httpModules&gt;
      &lt;/system.web&gt;
      &lt;system.codedom&gt;
          &lt;compilers&gt;
              &lt;compiler language="c#;cs;csharp" extension=".cs" warningLevel="4" type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"&gt;
                  &lt;providerOption name="CompilerVersion" value="v3.5"/&gt;
                  &lt;providerOption name="WarnAsError" value="false"/&gt;
              &lt;/compiler&gt;
              &lt;compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" warningLevel="4" type="Microsoft.VisualBasic.VBCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"&gt;
                  &lt;providerOption name="CompilerVersion" value="v3.5"/&gt;
                  &lt;providerOption name="OptionInfer" value="true"/&gt;
                  &lt;providerOption name="WarnAsError" value="false"/&gt;
              &lt;/compiler&gt;
          &lt;/compilers&gt;
      &lt;/system.codedom&gt;
      &lt;!-- 
          The system.webServer section is required for running ASP.NET AJAX under Internet
          Information Services 7.0.  It is not necessary for previous version of IIS.
      --&gt;
      &lt;system.webServer&gt;
          &lt;validation validateIntegratedModeConfiguration="false"/&gt;
          &lt;modules&gt;
              &lt;remove name="ScriptModule"/&gt;
              &lt;add name="ScriptModule" preCondition="managedHandler" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
          &lt;/modules&gt;
          &lt;handlers&gt;
              &lt;remove name="WebServiceHandlerFactory-Integrated"/&gt;
              &lt;remove name="ScriptHandlerFactory"/&gt;
              &lt;remove name="ScriptHandlerFactoryAppServices"/&gt;
              &lt;remove name="ScriptResource"/&gt;
              &lt;add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
              &lt;add name="ScriptHandlerFactoryAppServices" verb="*" path="*_AppService.axd" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
              &lt;add name="ScriptResource" preCondition="integratedMode" verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
          &lt;/handlers&gt;
      &lt;/system.webServer&gt;
      &lt;runtime&gt;
          &lt;assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"&gt;
              &lt;dependentAssembly&gt;
                  &lt;assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35"/&gt;
                  &lt;bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/&gt;
              &lt;/dependentAssembly&gt;
              &lt;dependentAssembly&gt;
                  &lt;assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35"/&gt;
                  &lt;bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/&gt;
              &lt;/dependentAssembly&gt;
          &lt;/assemblyBinding&gt;
      &lt;/runtime&gt;
  &lt;/configuration&gt;
  </code></pre>
  
  <ol>
  <li>Do I need to Installed something else before installing AjaxToolKit file ?</li>
  <li>Or do I have to do some other modification in web.config file ?</li>
  </ol>
  
  <p>Any help will be honored... Thanks in Advance</p>