netcoreapp3.0 
namespace Microsoft.AspNetCore.SignalR.Protocol
{
    public class HandshakeResponseMessage : HubMessage
    {
        public HandshakeResponseMessage(int? minorVersion, string error);
    }
}
.NET
5.06.07.08.09.010.011.0
.NET Core
3.03.1
Information specific to netcoreapp3.0
Assembly

Microsoft.AspNetCore.SignalR.Common , Version=3.0.0.0, PublicKeyToken=adb9793829ddae60

Referencing

Your project needs a package reference to Microsoft.AspNetCore.App.

Package Microsoft.AspNetCore.App (3.0.0-preview3-19153-02) netcoreapp3.0
Preview This API is contained in a prerelease package.
Platform Restrictions

This framework does not have platform annotations.

  • Built-in API
  • Package-provided API