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I know that this topic is out of date, but I've just overcome the same problem and my resolution is not related to any one of the listed here.
The issue is that in my project properties the parameter "Output path" (Build->Output) was a folder different from just "bin\". After changing it to bin\, reopening the Studio and rebuilding my project, everything worked out!
Hopefully, it might help someone.