Question

I have a class library that uses System.Web.Mvc version 3 and System.Web.WebPages version 1. After installing Visual Studio 2012 (MVC version 4) I have a problem compiling this class library in Visual Studio 2010:

Assembly 'System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' uses 'System.Web.WebPages, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' which has a higher version than referenced assembly 'System.Web.WebPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' c:\Program Files\Microsoft ASP.NET\ASP.NET MVC 4\Assemblies\System.Web.Mvc.dll

In this project I do not want to use MVC 4 yet.

Answer 1

I opened the .csproj file in a text editor and found the following line:

<Reference Include="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
  <SpecificVersion>False</SpecificVersion>
  <HintPath>C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 3\Assemblies\System.Web.Mvc.dll</HintPath>
</Reference>

I noticed the HintPath didn’t exists on my machine (Windows 7 32-bit), so apparently Visual Studio automatically takes the latest version (probably in the GAC). I removed System.Web.Mvc from the project references and added it again by browsing to the right path. The .csproj now looks like this:

<Reference Include="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
  <SpecificVersion>False</SpecificVersion>
  <HintPath>..\..\..\..\..\..\..\..\Program Files\Microsoft ASP.NET\ASP.NET MVC 3\Assemblies\System.Web.Mvc.dll</HintPath>
</Reference> 

Also make sure the Version argument is set to 3.0.0.0.