On a 32-bit Win 7 machine, I created a simple WPF app and I am getting this error when I instantiate a class derived from DbContext:
Message=The Entity Framework provider type 'Npgsql.NpgsqlServices, Npgsql.EntityFramework' registered in the application config file for the ADO.NET provider with invariant name 'Npgsql' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information.

I used Nuget package installer to install Npgsql 3.0.2 and EntityFramework.Npgsql 3.0.2, The assembly names that appear in VS13 references folder for those are, respectively, Npgsql and EntityFramework6.Npgsql. I copied and installed both of those .dll files in GAC in c:\program files\microsoft sdks\windows\v7.0A\bin \netfx 4.0 tools and c:\program files\microsoft sdks\windows\v8.1\bin \netfx 4.0 tools.

I also added this to machine.config:

 <system.data>
    <DbProviderFactories>
      <add name="Npgsql Data Provider" invariant="Npgsql" description=".Net Data Provider for PostgreSQL" type="Npgsql.NpgsqlFactory, Npgsql, Version=3.0.2.0, Culture=neutral, PublicKeyToken=5d8b90d52f46fda7" support="FF" />
    </DbProviderFactories>

Any ideas or suggestions? Thank you.