title: sgen.exe build error "Unable to load one or more of the requested types"
body: <p>I am building a solution which contains several solutions. All but one of them build without any problems.  The problematic one emits the following message: </p>
  
  <blockquote>
    <p>Error 2   Unable to load one or more of the requested types. Retrieve
    the LoaderExceptions property for more
    information.  J:\MyPlugins\MyPlugin1\SGEN MyPlugin1</p>
    
    <p>I turned on the verbose output in Visual Studio and I got the
    following: C:\Program Files (x86)\Microsoft
    SDKs\Windows\v8.0A\bin\NETFX 4.0 Tools\sgen.exe  /assembly:</p>
  </blockquote>
  
  <p>I checked the output with FusionLog and everything loaded correctly. This turned out to be a red herring.  I decided to run the build again with the verbosity turned up. I got the following:</p>
  
  <blockquote>
    <p>Microsoft (R) Xml Serialization support utility [Microsoft (R) .NET
    Framework, Version 4.0.30319.17929] Copyright (C) Microsoft
    Corporation. All rights reserved.   If you would like more help,
    please type "sgen /?". SGEN : error : Unable to load one or more of
    the requested types. Retrieve the LoaderExceptions property for more
    information. The command exited with code 1. Done executing task
    "SGen" -- FAILED.</p>
    
    <p>C:\Program Files (x86)\Microsoft SDKs\Windows\v8.0A\bin\NETFX 4.0
    Tools\sgen.exe /assembly:":\MyPlugins\MyPlugin1.dll" /proxytypes
    /reference:"J:\MyPlugins\MyPlugin1\packages\FluentValidation.3.4.6.0\lib\Net40\FluentValidation.dll"
    /reference:"C:\Program Files (x86)\Reference
    Assemblies\Microsoft\Framework.NETFramework\v4.0\mscorlib.dll"
    /reference:"J:\MyPlugins\MyPlugin1\Libraries\Core\bin\Release\Core.dll"
    /reference:"J:\MyPlugins\MyPlugin1\Libraries\Services\bin\Release\Services.dll"
    /reference:"J:\MyPlugins\MyPlugin1\Presentation\Web.Framework\bin\Release\Web.Framework.dll"
    /reference:"C:\Program Files (x86)\Reference
    Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Core.dll"
    /reference:"C:\Program Files (x86)\Reference
    Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Data.dll"
    /reference:"C:\Program Files (x86)\Reference
    Assemblies\Microsoft\Framework.NETFramework\v4.0\System.dll"
    /reference:"C:\Program Files (x86)\Reference
    Assemblies\Microsoft\Framework.NETFramework\v4.0\System.EnterpriseServices.dll"
    /reference:"C:\Program Files (x86)\Reference
    Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Web.dll"
    /reference:"C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC
    4\Assemblies\System.Web.Mvc.dll" /reference:"C:\Program Files
    (x86)\Reference
    Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Web.Services.dll"
    /reference:"C:\Program Files (x86)\Reference
    Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Xml.dll"</p>
  </blockquote>
  
  <p>What is causing this error and how do I fix it short of turning off SGEN?  FYI, I didn't write the code.</p>