title: Invalid route in ASP.net MVC Core 2 app shows blank page
body: <p>I have a new empty asp.net MVC Core 2 web app. When going to a non-existant route rather than coming with an error page it just shows a blank page.</p>
  
  <p>The site is setup with IIS. I'm in Development environment. I've tried commenting <code>app.UserExceptionHandler("/Home/Error");</code> and <code>app.UseDeveloperExceptionPage();</code> - I've tried them individually in my environment. None of it makes any difference, just blank pages returned.</p>
  
  <p>Why aren't errors being returned when I enter an invalid route &amp; how can I see them?</p>
  
  <p>I also ran in debugging on the /Home/Error ActionMethod to see if it was being hit - it never was. Thanks.</p>