using System;

using Newtonsoft.Json;

​

public class Program

{

    public static void Main()

    {

        var settings = new JsonSerializerSettings

            {

                NullValueHandling = NullValueHandling.Ignore

            };

​

            var convertedMessage = JsonConvert.DeserializeObject<JsonO>(@"{

""StartDate"": null,

  ""EndDate"": null

}", settings);

        Console.WriteLine(convertedMessage.StartDate);

    }

    public class JsonO

        {

            public DateTime StartDate { get; set; }

            public DateTime EndDate { get; set; }

        }

}