<PackageReference Include="NETStandard.Library" Version="2.0.2" />

System.Net.WebSockets.WebSocketError

public enum WebSocketError
namespace System.Net.WebSockets { public enum WebSocketError { ConnectionClosedPrematurely = 8, Faulted = 2, HeaderError = 7, InvalidMessageType = 1, InvalidState = 9, NativeError = 3, NotAWebSocket = 4, Success = 0, UnsupportedProtocol = 6, UnsupportedVersion = 5 } }