title: System.Runtime 4.0.10.0 missing on Server 2012r2 after website upgrade to MVC5.1
body: <p>Website works fine locally on Windows 8.1, but after publishing to Server 2012R2, certain pages get an error saying the following:</p>
  
  <p>Exception message: c:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\root\b306803a\3271e75d\App_Web_sign-in.cshtml.1d427dc2.p4pq8o_l.0.cs(30): error CS0012: The type 'System.Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Runtime, Version=4.0.10.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.</p>
  
  <p>I can't work out what or how is referencing that System.Runtime dll. What might I be missing and how might I track it down?</p>