Unable to find or load Npgsql with Entity Framework
<p>I am totally lost. In Visual Studio 2015, I created a WCF Library Service project and defined the service and service interface. </p>

<p>EntityFramework, EntityFramework.SqlServer, EntityFramework6.Npgsql, and Npgsql was installed with the NuGet console:</p>

<ul>
<li>PM> Install-Package EntityFramework6.Npgsql -Version 3.0.5</li>
</ul>

<p>Setting the library service as startup then starting debug (f5) correctly
read the available procedures. However, upon testing any procedure in the
WcfSvcHost, I get the following error:</p>

<blockquote>
  <p>The ADO.NET provider with invariant name 'Npgsql' is either not
  registered in the machine or application config file, or could not be
  loaded. See the inner exception for details.</p>
</blockquote>

<p>What did I do wrong?</p>

<p>Here is the App.config file:</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;configuration&gt;
  &lt;configSections&gt;
    &lt;!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 --&gt;
    &lt;section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" /&gt;
    &lt;!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 --&gt;
  &lt;/configSections&gt;
  &lt;appSettings&gt;
    &lt;add key="aspnet:UseTaskFriendlySynchronizationContext" value="true" /&gt;
  &lt;/appSettings&gt;
  &lt;system.web&gt;
    &lt;compilation debug="true" /&gt;
  &lt;/system.web&gt;
  &lt;!-- When deploying the service library project, the content of the config file must be added to the host's 
  app.config file. System.Configuration does not support config files for libraries. --&gt;
  &lt;system.serviceModel&gt;
    &lt;services&gt;
      &lt;service name="NovaMedicalService.MedicalService"&gt;
        &lt;endpoint address="" binding="basicHttpBinding" contract="NovaMedicalService.IMedicalService"&gt;
          &lt;identity&gt;
            &lt;dns value="localhost" /&gt;
          &lt;/identity&gt;
        &lt;/endpoint&gt;
        &lt;endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /&gt;
        &lt;host&gt;
          &lt;baseAddresses&gt;
            &lt;add baseAddress="http://localhost:8733/Design_Time_Addresses/NovaMedicalService/MedicalService/" /&gt;
          &lt;/baseAddresses&gt;
        &lt;/host&gt;
      &lt;/service&gt;
    &lt;/services&gt;
    &lt;behaviors&gt;
      &lt;serviceBehaviors&gt;
        &lt;behavior&gt;
          &lt;!-- To avoid disclosing metadata information, 
          set the values below to false before deployment --&gt;
          &lt;serviceMetadata httpGetEnabled="True" httpsGetEnabled="True" /&gt;
          &lt;!-- To receive exception details in faults for debugging purposes, 
          set the value below to true.  Set to false before deployment 
          to avoid disclosing exception information --&gt;
          &lt;serviceDebug includeExceptionDetailInFaults="False" /&gt;
        &lt;/behavior&gt;
      &lt;/serviceBehaviors&gt;
    &lt;/behaviors&gt;
  &lt;/system.serviceModel&gt;
  &lt;entityFramework&gt;
    &lt;defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework"&gt;
      &lt;parameters&gt;
        &lt;parameter value="v12.0" /&gt;
      &lt;/parameters&gt;
    &lt;/defaultConnectionFactory&gt;
    &lt;providers&gt;
      &lt;provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" /&gt;
      &lt;provider invariantName="Npgsql" type="Npgsql.NpgsqlServices, EntityFramework6.Npgsql" /&gt;
    &lt;/providers&gt;
  &lt;/entityFramework&gt;
  &lt;connectionStrings&gt;
    &lt;add name="chaosEntities" connectionString="metadata=res://*/ChaosModel.csdl|res://*/ChaosModel.ssdl|res://*/ChaosModel.msl;provider=Npgsql;provider connection string=&amp;quot;Database=chaos;Host=localhost;Password=yuyuyu;Username=ooosos&amp;quot;" providerName="System.Data.EntityClient" /&gt;
  &lt;/connectionStrings&gt;
&lt;/configuration&gt;
</code></pre>

<p>Can someone please help? I am totally lost.</p>

<p>TIA</p>