title: Revert EntityFramework 6.0.0.0 to 5.0.0.0
body: <p>I am attempting to configure ASP.NET 4.5 with WebAPI using PostgresSQL and Entity framework. I have discovered that there are two separate builds of the Postgres driver Npgsql. Version 2.0.12.0 supports EF 5.0.0.0. There is a separate build (which is according to the documentation incorrectly labeled as 2.0.13.91) supporting EF 6.0.0.0. I don't care which versions I use as long as I can get one to work properly. I get an error attempting to use EF 6.0.0.0 and I am currently trying to get 5.0.0.0 to work (the error from 6.0.0.0 is a separate issue and I will post about that separately if necessary).</p>
  
  <p>The problem now is that apparently because I already installed EF 6.0.0.0 at one point, I cannot fully downgrade to EF 5.0.0.0. I have reverted all references that I can find and I have only EF 5.0.0.0 installed, but when I deploy the web API application or attempt to execute code that uses the Npgsql driver, I get:</p>
  
  <pre><code>A first chance exception of type 'System.IO.FileLoadException' occurred in System.Data.Entity.dll
  A first chance exception of type 'System.IO.FileLoadException' occurred in EntityFramework.dll
  iisexpress.exe Error: 0 : Operation=ReflectedHttpActionDescriptor.ExecuteAsync, Exception=System.IO.FileLoadException: Could not load file or assembly 'EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
  File name: 'EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'
     at Npgsql.NpgsqlFactory.GetService(Type serviceType)
     at System.Data.Common.DbProviderServices.GetProviderServices(DbProviderFactory factory)
  </code></pre>
  
  <p>I don't know where the specification of 6.0.0.0 is coming from. I updated all the version specifications in <code>web.config</code>. I have uninstalled and reinstalled 5.0.0.0. I even uninstalled and reinstalled the Visual Studio update package for MVC4. The EntityFramework package listed in Nuget is 5.0.0.0. All of the referenced assemblies in the package specify EF 5.0.0.0. I rebuilt Npgsql and registered the rebuilt <code>Npgsql.dll</code> and <code>Mono.Security.dll</code> with <code>gacutil.exe</code>. What is pointing to 6.0.0.0 and how do I revert it?</p>
  
  <p>TL;DR</p>
  
  <p>The located assembly is 5.0.0.0, which is correct. For some reason it's looking for 6.0.0.0 and I can't figure out why.</p>