Can anyone explain a perse error like this one: "Method 'get_EnableCdn' in type 'System.Web.UI.ScriptManager' from assembly 'System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' does not have an implementation."

I got this error in a web application when I was   upgrading  from a Visual Studio 2008 project to a Visual Studio 2010 project.

The solution was to remove the following section from the web.config file:

<runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
        <dependentAssembly>
            <assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35"/>
            <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/>
        </dependentAssembly>
        <dependentAssembly>
            <assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35"/>
            <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/>
        </dependentAssembly>
    </assemblyBinding>
</runtime>