The type 'System.Web.UI.ScriptManager' exists in both 'System.Web.Extensions\3.5.0.0__31bf3856ad364e35\System.Web.Extensions.dll' and 'System.Web.Extensions\1.0.61025.0__31bf3856ad364e35\System.Web.Extensions.dll'

Using VS.NET 2005 i was on a project and tried using the TABS in AjaxControl kit
I was sure the version was 1.0.61025.0 but anytime i compile the project i get the error :

The type 'System.Web.UI.ScriptManager' exists in both 'c:\Windows\assembly\GAC_MSIL\System.Web.Extensions\3.5.0.0__31bf3856ad364e35\System.Web.Extensions.dll' and 'c:\Windows\assembly\GAC_MSIL\System.Web.Extensions\1.0.61025.0__31bf3856ad364e35\System.Web.Extensions.dll'   

I did all i knew to add the right TAGS in web.config but with no luck. Funny enough i could get the page to load on my local server but not on production when i deploy it.
I later created another project using VS.NET 2008 with the same setup and looking at the web.config noticed there was other tags that was included that wasn't in the previous project e.g

<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>

The Solution:
After i added these tags above  to the web.config before the end tag </configuration>
It worked like a charm

Enjoy and save your time

Ajax - Request for the permission of type 'System.Web.AspNetHostingPermission,

To resolve this issue, you must change your development machine .net security configuration since you are accessing items across the network.
In the event that you need this ability at runtime, you must change the trust level in your config file to full.

However, since this is only in development, I can change my local PC's security by going to Start > Control Panel > Administrative Tools > Microsoft .NET Framework 2.0 Configuration.

After it fully loads (sometimes takes a bit), fully expand My Computer in the navigation tree and click Runtime Security Policy. In the right hand pane, choose Adjust Zone Security.

Leave the default option (Make changes to this computer) and hit next. Choose Local Intranet and change the trust level to Full Trust.
Then choose next and then finish. Restart Visual Studio 2005 and you should be all set.

Hope that helps
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