<PackageReference Include="NETStandard.Library" Version="2.0.0-preview2-25401-01" />

System.Text.DecoderFallbackException

namespace System.Text { public sealed class DecoderFallbackException : ArgumentException { public byte[] BytesUnknown { get; } public int Index { get; } public DecoderFallbackException(); public DecoderFallbackException(string message); public DecoderFallbackException(string message, byte[] bytesUnknown, int index); public DecoderFallbackException(string message, Exception innerException); } }