When I load up my VS2013 projects in 2015, all my razor views are filled with red squiggly underlines.
@model, @Scripts @url, @Html.Partial, lambda expressions
I've upgraded to mvc5 and so forth to razer 3. It solved my issue.
I followed this instructions :
http://www.asp.net/mvc/overview/releases/how-to-upgrade-an-aspnet-mvc-4-and-web-api-project-to-aspnet-mvc-5-and-web-api-21