ASP.NET MVC 4 breaks ASP.NET MVC 3 projects

Question

After installing the ASP.NET MVC 4 Developer Preview, I can no longer open MVC 3 projects, with the following error message:

The project type is not supporte         


        

Answer 1

Check the reference to System.Web.Mvc.dll file in your reference. Make sure its pointing to C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 3\Assemblies\System.Web.Mvc.dll

If its pointing to the one under ASP.NET MVC 4 directory then open your project file in a notepad. Look for

  False

This should be changed to