SignalR ApplicationUserManager在使用webSockets传输时被释放

我已将SignalR添加到现有的MVC项目中，并尝试使用MVC中的相同ApplicationUserManager将用户加载到集线器上下文中 .

连接完成后，我调用一些这样的服务器方法：

var alertsHub = $.connection.monitoringHub;

        $(function() {
            alertsHub.client.processAlertChange = function (name, alert) {
                console.log(alert);
            };

            //start the connection
            $.connection.hub.start().done(function () {
                console.log("Connected, transport = " + $.connection.hub.transport.name);
                alertsHub.server.subscribeToMonitor();
            });
        });

在我的Hub方法中有一个电话

CurrentUser = ConnectedUsers.GetOrAdd(this.Context.ConnectionId, UserManager.FindByName(this.Context.User.Identity.Name));

UserManager就是这样的属性

protected static ConcurrentDictionary<string, ApplicationUser> ConnectedUsers = new ConcurrentDictionary<string, ApplicationUser>();

    private ApplicationUserManager _userManager;
    public ApplicationUserManager UserManager
    {
        get
        {
            if (_userManager == null)
            {
                _userManager = Context.Request.GetHttpContext().GetOwinContext().GetUserManager<ApplicationUserManager>();
            }
            return _userManager;
        }
    }
    protected ApplicationUser CurrentUser { get; set; }

问题是，当使用webSockets传输时，我收到错误“无法访问已处置的对象”

SignalR: webSockets transport connected. Initiating start request.
SignalR: The start request succeeded. Transitioning to the connected state.
SignalR: Now monitoring keep alive with a warning timeout of 13333.333333333332, keep alive timeout of 20000 and disconnecting timeout of 300000
Connected to monitoringHub, transport = webSockets
SignalR: Invoking monitoringhub.SubscribeToMonitor
SignalR: monitoringhub.SubscribeToMonitor failed to execute. Error: Cannot access a disposed object.
Object name: 'ApplicationUserManager'.

但！当我强制serverSentEvents传输时 - 没有错误，一切都很好 . 为什么？以及它如何修复......

我的Startup.cs

ConfigureAuth(app);

        // Any connection or hub wire up and configuration should go here
        var hubConfiguration = new HubConfiguration();
        hubConfiguration.EnableDetailedErrors = true;

        app.MapSignalR("/sr", hubConfiguration);

        GlobalHost.HubPipeline.RequireAuthentication();
        GlobalHost.Configuration.ConnectionTimeout = TimeSpan.FromSeconds(120);
        GlobalHost.Configuration.DisconnectTimeout = TimeSpan.FromSeconds(300);
        GlobalHost.Configuration.KeepAlive = TimeSpan.FromSeconds(10);