title: Can't use System.Configuration.Configuration manager in a .NET Standard2.0 library on .NET FX4.6
body: <p>I have an assembly created in <em>NetStandard2.0</em>. It reads AppSettings using <strong>System.Configuration.ConfigurationManager</strong>. I have installed nuget package of <strong>System.Configuration.ConfigurationManager</strong> with version 4.4.X which is suitable for <em>NetStandard2.0</em>.</p>
  
  <p>When I refer this assembly in console app (.Net Core) it is reading AppSettings properly, but when I refer this assembly in old .NetFramework(4.6.X) console app it is not working and throwing an exception.</p>
  
  <p>Please see the code below.</p>
  
  <p><strong>Assembly 1: NetStandard 2.0</strong></p>
  
  <p><strong>Nuget: System.Configuration.ConfigurationManager 4.4.0</strong></p>
  
  <pre><code>using System.Configuration;
  
  namespace Bootstrapper.Lib
  {
     public class Bootstrapper
     {
       public Bootstrapper()
       {
  
       }
  
       public void LoadAppSettings()
       {
           string serachPattern= 
           ConfigurationManager.AppSettings["AssemblySearchPattern"];
       }
    }
  
  }
  </code></pre>
  
  <p><strong>Console App: NetFx 4.6.X</strong></p>
  
  <pre><code>using System;
  using Bootstrapper.Lib;
  namespace Bootstrapper.Console
  {
    class Program
    {
      static void Main(string[] args)
      {
          new Bootstrapper().LoadAppSettings();
      }
    }
  }
  </code></pre>
  
  <p><strong>Exception After Run:</strong></p>
  
  <pre><code>'Could not load file or assembly 'System.Configuration.ConfigurationManager, 
   Version=4.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' or one 
   of its dependencies. The system cannot find the file specified.'
  </code></pre>
  
  <p>It will work with Console App developed using .NetCore.</p>
  
  <p>Please help!!!</p>