If a project requires IIS to run, the IIS needs to be enabled for completing its imigration.
VS2012 comes with Silverlight Toolkit managed by NeGet, but Silverlight SDK 5 needs to be installed to run any Silverlight projects.
When upgrading .Net projects to .Net 4.5, MVC attribute "Compare" needs its full namespace.
System.Web.WebPages needs to be removed from References to remedy error: The type 'System.Web.Mvc.ModelClientValidationRule' exists in both 'c:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 3\Assemblies\System.Web.Mvc.dll' and 'c:\Program Files (x86)\Microsoft ASP.NET\ASP.NET Web Pages\v2.0\Assemblies\System.Web.WebPages.dll'
System.Data.Services and System.Data.Services.Client need to be removed to use EF5.0. AddObject() needs to be replaced with Add(), Delete() with Remove() of DbSet(),
VS2012 does not support the traditional setup project anymore, but the new way of publishing is much better and one should use it anyway.