Formatting DateTime in ASP.NET Core 3.0 using System.Text.Json

Solved with a custom formatter. Thank you Panagiotis for the suggestion.

public class DateTimeConverter : JsonConverter<DateTime>{    public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)    {        Debug.Assert(typeToConvert == typeof(DateTime));        return DateTime.Parse(reader.GetString());    }    public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)    {        writer.WriteStringValue(value.ToUniversalTime().ToString("yyyy'-'MM'-'dd'T'HH':'mm':'ssZ"));    }}// in the ConfigureServices()services.AddControllers()    .AddJsonOptions(options =>     {         options.JsonSerializerOptions.Converters.Add(new DateTimeConverter());     });

Migrating to Core 3 I had to replace System.Text.Json to use Newtonsoft again by :

services.AddControllers().AddNewtonsoftJson();

But I was having same issue with UTC dates in an Angular app and I had to add this to get dates in UTC:

services.AddControllers().AddNewtonsoftJson(       options => options.SerializerSettings.DateTimeZoneHandling = DateTimeZoneHandling.Utc);

In your case you should be able to do this:

services.AddControllers().AddNewtonsoftJson(options =>    {        options.SerializerSettings.DateTimeZoneHandling = Newtonsoft.Json.DateTimeZoneHandling.Utc;        options.SerializerSettings.DateFormatString = "yyyy'-'MM'-'dd'T'HH':'mm':'ssZ";    });

It works and I hope it helps...