SignalR：“用户身份在主动SignalR连接期间无法更改”与windows auth网站出错

I have an MVC 5 website running signalR 2.1.0 using Windows Authentication. Because I'm using windows auth login/logout is handled automatically by IIS. Occassionally I'm getting a 403 error saying "Unrecognized user identity. The user identity cannot change during an active SignalR connection." This doesn't happen all the time, and I can't seem to find a pattern to when it does and does not work. Has anyone else encountered this?I have an MVC 5 website running signalR 2.1.0 u