asp.net mvc - Build Errors - 'System.Web.Mvc.ModelClientValidationRule' Conflicts

Question

I am trying to 'build' my MVC3 web app in VS2010 however keep getting the following error:

Error 2 The type 'System.Web.Mvc.ModelClientValidationRule' exists in both 'c:Program Files (x86)Microsoft ASP.NETASP.NET MVC 3AssembliesSystem.Web.Mvc.dll' and 'c:Program Files (x86)Microsoft ASP.NETASP.NET Web Pagesv2.0AssembliesSystem.Web.WebPages.dll' C:UsersrownpDocumentsVisual Studio 2010ProjectsCabCabModelsAccountModels.cs 223 28 Cab

Also, every time I open the solution, it prompts me with the following:

I install via Web Platform Installer and it installs successfully however the message reappears every time I open the solution.

Can anyone offer any guidance?

Thanks Paul

Answer 1

After installing MVC4 beta today, a few of my MVC 3 projects would not compile. (ModelClientValidationRule conflict) The fix was:

Edit:

ProjectName.csproj

Change

<Reference Include="System.Web.WebPages"/> 

To

<Reference Include="System.Web.WebPages, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL "/>