WPF and RDP Questions

Dear WPF Team at Microsoft,

It seems like when a user reconnects to a Windows Server 2008/2016 Session using Remote Desktop (RDP protocol), this causes a call to the "OnStartup(StartupEventArgs e)" method in many WPF applications (when I say "reconnect" I mean, users do not log off but rather close the RDP session by clicking on the "X" to close the session window. Later they connect back using remote desktop - this last action causes a crash on some WPF apps. Also worth specifying that the WPF app was never closed. It was opened when they left and it crashed when they reconnected to their session).

I wanted to reach out to you all to understand if this is a bug in WPF or in Windows Server…

Short snippet of Code:

```
protected override void OnStartup(System.Windows.StartupEventArgs e)

{

base.OnStartup(e);

string AppDomainName = "My new domain";

ShutdownMode = ShutdownMode.OnLastWindowClose;

var my_domain = AppDomain.CreateDomain(AppDomainName, AppDomain.CurrentDomain.Evidence, AppDomain.CurrentDomain.SetupInformation);

CrossAppDomainDelegate MyActionLoad = () =>

{

Thread thread = new Thread(() =>

{

var app = new Application();

app.Run(); // <-- THIS CRASHES WHEN RDP IS RE-ESTABLISHED.

});

thread.SetApartmentState(ApartmentState.STA);

thread.Start();

};

my_domain.DoCallBack(MyActionLoad);

my_domain.DoCallBack(() => Application.Current.Dispatcher.Invoke(new Action(Application.Current.Shutdown)));

new Action(

() =>

{

Thread.Sleep(500);

AppDomain.Unload(my_domain);

}).BeginInvoke(null, null);

}

```
3 QUESTIONS:

Why is RDP triggering this call to OnStartup method? (And why, no matter what condition I put in the source code before it, it always crashes in the app.Run() statement, even if I check for special flags like if i write to a file and check that A signal file exists as a way to prevent calling this run method again, etc - somehow the code skips and goes directly to app.Run()).

Is this a bug in Windows Server Server 2016? (Please note that I have seen this behavior happen in Windows Server 2008, too). My server is on Microsoft Windows Server 2016 Standard (Version 10.0.14393). Is there a patch or service pack or something to fix this problem?

Any recommendation to avoid having the "app.Run()" method in the "OnStartup" to get triggered/called AFTER someone reconnects to the server via RDP?

Thank you