The user identity cannot change during an active SignalR connection

This error may be seen if authentication is being used, and the client is logged out before the connection is stopped. The solution is to stop the SignalR connection before logging the client out.

无法识别的用户标识。在 SignalR 连接处于活动状态期间无法更改用户标识

官方有详细的文档：

http://www.asp.net/signalr/overview/signalr-20/troubleshooting-and-debugging/troubleshooting