UWP(Windows 10)后台任务-调用COM组件时返回错误HRESULT E_FAIL(VS2017)

我有一个UWP Windows 10应用程序,打算用作信号器客户端。我以前就有过这样的工作,但最近开始出现这样的错误: Error HRESULT E_FAIL has been returned from a call to a COM component ApplicationTrigger .

这是我应用程序中的代码。XML:

private void SignalR()
{
    _hubConnection = new HubConnection("http://localhost/hollerhub");
    _hubConnection.Credentials = CredentialCache.DefaultCredentials;
    _toast = _hubConnection.CreateHubProxy("toast");
    _toast.On<string>("broadcastMessage", msg =>
    {
        var localSettings = Windows.Storage.ApplicationData.Current.LocalSettings;
        localSettings.Values["toastInfo"] = msg;
        var appTrigger = new ApplicationTrigger();
        appTrigger.RequestAsync().GetResults();  // <--- This is where the error is thrown
    });

    _hubConnection.Start(); 
}

后台任务在应用程序启动时注册,但 应用程序触发器 在失败之前未达到我的后台任务代码。它正在接收信号器消息。