netcoreapp2.0 
namespace System.Text.Json.Serialization
{
    public enum JsonUnknownDerivedTypeHandling
    {
        FailSerialization = 0
    }
}
.NET
5.06.07.08.09.010.0
.NET Core
2.02.12.23.03.1
.NET Framework
4.6.14.6.24.74.7.14.7.24.84.8.1
.NET Standard
2.02.1
Information specific to netcoreapp2.0
Assemblies

System.Text.Json , Version=10.0.0.0, PublicKeyToken=cc7b13ffcd2ddd51

System.Text.Json , Version=9.0.0.0, PublicKeyToken=cc7b13ffcd2ddd51

Referencing

Your project needs a package reference to System.Text.Json.

Package System.Text.Json (10.0.0-preview.1.25080.5) netstandard2.0
Platform Restrictions

This framework does not have platform annotations.

  • Built-in API
  • Package-provided API