<PackageReference Include="NETStandard.Library" Version="2.0.1" />

System.Text.EncoderFallbackException

namespace System.Text { public sealed class EncoderFallbackException : ArgumentException { public char CharUnknown { get; } public char CharUnknownHigh { get; } public char CharUnknownLow { get; } public int Index { get; } public EncoderFallbackException(); public EncoderFallbackException(string message); public EncoderFallbackException(string message, Exception innerException); public bool IsUnknownSurrogate(); } }