I upgraded my hobby development PC from Windows 8.1 Preview, to the real deal, Windows 8.1 Release version… First disappointment, was that all my programs have to be reinstalled, but this is another story/rant.
So, I upgraded to Visual Studio 2013, and immediately tried to load one of my Visual Studio 2012 projects, and…
What the …. Microsoft is at it again????
I was fiddling around for a few minutes… Then, I tried to change to port number on the project’s web property settings, and it suddenly worked!!!
After that, I simply followed the MVC4 to MVC5 upgrade instructions here: http://www.asp.net/mvc/tutorials/mvc-5/how-to-upgrade-an-aspnet-mvc-4-and-web-api-project-to-aspnet-mvc-5-and-web-api-2
Hope this “tip” helps.