Duplicate reference to mscorlib CS1703 Error
<p>So I am currently working on migrating an application that was living on a windows 2k3 server to a machine running Windows 2012 server. After moving the site over, setting the app pool correctly and configuring the rest of the site, I am receiving this error. After doing some research it appears to be a reference to one of the main .net core libraries, and they are added by default to any project started in Visual Studio. I have not been able to find them referenced within the project anywhere. I've pretty much exhausted google search and have not been able to find a solution to this problem.</p>

<p>The error:</p>

<blockquote>
  <p>Compilation Error</p>
  
  <p>Description: An error occurred during the compilation of a resource
  required to service this request. Please review the following specific
  error details and modify your source code appropriately. </p>
  
  <p>Compiler Error Message: CS1703: An assembly with the same identity
  'mscorlib, Version=4.0.0.0, Culture=neutral,
  PublicKeyToken=b77a5c561934e089' has already been imported. Try
  removing one of the duplicate references.</p>
  
  <p>Source Error:</p>
  
  <p>[No relevant source lines]</p>
  
  <p>Source File:    Line: 0 </p>
  
  <p>Show Detailed Compiler Output:</p>
  
  <p>C:\Windows\SysWOW64\inetsrv> "C:\Program Files (x86)\LINQ
  Preview\Bin\csc.exe" /noconfig /fullpaths
  @"C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET
  Files\cts\67846b7a\f5d88660\sfsllqyb.cmdline"</p>
  
  <p>Microsoft (R) Visual C# 2005 Compiler version 8.00.50916 for Microsoft
  (R) Windows (R) 2005 Framework version 2.0.50727 Copyright (C)
  Microsoft Corporation 2001-2005. All rights reserved.</p>
  
  <p>c:\Windows\Microsoft.NET\Framework\v4.0.30319\mscorlib.dll: error
  CS1703: An assembly with the same identity 'mscorlib, Version=4.0.0.0,
  Culture=neutral, PublicKeyToken=b77a5c561934e089' has already been
  imported. Try removing one of the duplicate references.
  c:\Windows\Microsoft.NET\Framework\v2.0.50727\mscorlib.dll: (Location
  of symbol related to previous error)</p>
  
  <p>Version Information: Microsoft .NET Framework Version:4.0.30319;
  ASP.NET Version:4.6.1069.1</p>
</blockquote>

<p>Would appreciate any insight.</p>