To upgrade your existing MVC 4 application to MVC 5 you need to go through a number of steps to replace the references and patch the web.config [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] . These steps are clearly explained in the original post, but when you're