visual studio 2k8 (and 2k10) cannot compile web application when gac assemblies are moved into global web.config

Question

I have numerous ASP.NET 3.5 web applications with verbose application-level web.config files which I wish to slim down and make more readable.

Visual Studio 2010 has just arrived and has already started "cleaning up" various sections of the web.config - so now is a perfect time for me to continue the good work and do the same in other areas of the web.config file.

Currently I have several third party assemblies all happily registered in the GAC, these are then referenced in each application-level Web.Config see below;

<configuration>
    <system.web>
        <compilation defaultLanguage="C#" debug="true">
            <assemblies>
                <add assembly="AjaxControlToolkit, Version=3.0.30512.20315, Culture=neutral, PublicKeyToken=28F01B0E84B6D53E"/>
                <add assembly="aspNetEmail, Version=3.5.2.0, Culture=neutral, PublicKeyToken=BC571E8DA1C1F543"/>
                <add assembly="aspNetDns, Version=3.0.0.0, Culture=neutral, PublicKeyToken=BC571E8DA1C1F543"/>
                <add assembly="Microsoft.Practices.EnterpriseLibrary.Common, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
                <add assembly="Microsoft.Practices.EnterpriseLibrary.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
            </assemblies>
        </compilation>
    </system.web>
</configuration>

I have moved the above compilation-node into the global web.config file located at Windows\Microsoft.NET\Framework64\v4.0.30319\Config\web.config - and the application runs just fine under IIS7 i.e. the application has no trouble finding these GAC'd assemblies.

however when I now compile (shift+ctrl+b) my web application in visual studio 2k8 or 2k10 I'm getting the familiar error "The type or namespace name 'aspNetDns' could not be found (are you missing a using directive or an assembly reference?)"

What do I have to do to get visual studio to recognise the whereabouts of these GAC'd libraries? I tried copying them into windows\system32 but no joy there...

help! :)

NB: I have also tried working with the machine.config but still no luck

Answer 1

Drag / drop the assemblies to c:\windows\assembly on your local machine where you are recompiling.

Answer 2

Solved it.

I needed to edit the global web.config in the x86 directory (as well as the x64 version) - the x86 version is obviously the one Visual Studio was looking at whilst compiling the app, whereas IIS was looking at the x64 version of the global web.config when running the app.