I want to serialize a large tree structure of different objects to a xml
file. To get a loose coupling design some classes have interface members. At
runtime I get an InvalidOperationException: Cannot serialize member XYZ
because it is an interface.

To boil the thing down to a test example:

   public interface IProblematicMember
   {
   }

   public class ProblematicMember: IProblematicMember
   {

   }

   public class DoesNotSerialize
   {
       private IProblematicMember problematicMember;

       public IProblematicMember ProblematicMember
       {
           get { return problematicMember; }
           set { problematicMember = value; }
       }
   }

   class Program
   {
       static void Main(string[] args)
       {
           DoesNotSerialize dns = new DoesNotSerialize();
           XmlSerializer mySerializer = new
XmlSerializer(typeof(DoesNotSerialize));
           StreamWriter myWriter = new StreamWriter("myFileName.xml");
           mySerializer.Serialize(myWriter, dns);
           myWriter.Close();
       }
   }

Is there any possibility to solve this, e.g. by implementing the
serialization by hand?

Thanks for your help,

Fabian