using System;

using System.Linq;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var ignoreNulls = new JsonSerializerSettings {

            NullValueHandling = NullValueHandling.Ignore,

        };

        Try(() => Console.WriteLine(JsonConvert.DeserializeObject<DateTime?>("null"))); // ok

        // Try(() => Console.WriteLine(JsonConvert.DeserializeObject<DateTime>("null", ignoreNulls))); // error

        ignoreNulls.Converters.Add(new AllowNullConverter());

        Try(() => Console.WriteLine(JsonConvert.DeserializeObject<DateTime>("null", ignoreNulls))); // ok

    }

    private static void Try(Action action) {

        try 

        {

            action();

        }

        catch (Exception ex)

        {

            Console.WriteLine(ex.ToString());

        }

    }

        class AllowNullConverter : JsonConverter

        {

            public override bool CanConvert(Type objectType)

            {

                return objectType == typeof(DateTime);

            }

​

            public override bool CanRead

            {

                get 

                {

                    return true;    

                }

            }

​

            public override bool CanWrite

            {

                get 

                {

                    return false;   

                }

            }

​

            public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

            {

                if (reader.TokenType == JsonToken.Null)

                {

                    return default(DateTime);

                }

​

                return reader.Value;

            }

​

            public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

            {

                throw new NotSupportedException();

            }

        }

}