using System;

using System.Text.Json;

using System.Text.Json.Serialization;

public class Program

{

    public static void Main()

    {

        string s = "\"/Date(1573581177000)/\"";

        var deserializeOptions = new JsonSerializerOptions();

        deserializeOptions.Converters.Add(new DateTimeConverter());

        DateTime dt = JsonSerializer.Deserialize<DateTime>(s, deserializeOptions);

        Console.WriteLine(dt);

    }

}

​

public class DateTimeConverter : JsonConverter<DateTime>

{

​

    public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)

    {

        var s = reader.GetString();

        s=s.Replace("/Date(","");

        s=s.Replace(")/","");

        long epoch = Convert.ToInt64(s);

        DateTimeOffset dateTimeOffset = DateTimeOffset.FromUnixTimeMilliseconds(epoch);

        return dateTimeOffset.UtcDateTime;

    }

​

    public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)

    {

        // Do some conversion here

    }

}

​

​