title: Losing session after file changed / uploaded
body: <p>I am currently having a strange issue with sessions, I've worked with MVC for quite a while and never had this in previous versions. Currently making a new system using MVC5 for the first time, all is well. Sessions are being set with no issues, however, if I modify a cshtml file in VS my session is killed.</p>
  
  <p>Also I have a file upload feature which works, but when you upload a file and then navigate to another page the session is gone again. This is working locally and also on a Windows Server box we use for sandboxing.</p>
  
  <p>Has something changed with the new versions of MVC regarding sessions? I've never had this before. I've got it set to use in-proc sessions, never normally needed to change anything but I have for the sake of things used cookieless, used cookies etc as options. Nothing seems to work.</p>
  
  <p>If anyone has an idea that would be great. </p>