title: InvalidOperationException: Can't compile a NewExpression with a constructor declared on an abstract class
body: <p>Getting an error when trying to retrieve objects from mongodb:</p>
  
  <blockquote>
    <p>InvalidOperationException: Can't compile a NewExpression with a
    constructor declared on an abstract class</p>
  </blockquote>
  
  <p>My class is:</p>
  
  <pre><code>public class App 
  {
      public List&lt;Feature&gt; Features { get; set; }
  }
  
  public abstract class Feature
  {
      public string Name { get; set; }
  }
  
  public class ConcreteFeature : Feature
  {
      public string ConcreteProp { get; set; }
  }
  </code></pre>
  
  <p>Not sure why it is having issues with abstractions. I see, mongodb recorded <code>_t: "ConcreteFeature"</code> type name, it has everything to deserialize it. I have no constructor in abstract class.</p>
  
  <p>Ideas?</p>