AppInstance.FindOrRegisterForKey("main").IsCurrent is always true

[JohnCido]

Describe the bug

I was trying to use the code in this repo to add single instance functionality to my app. But as described in the title. The AppInstance.FindOrRegisterForKey("main").IsCurrent is always true. So I can't use this to terminate the existing app instance at all.

Steps to reproduce the bug

1. Create a new Solution using WinUI 3 single package template
2. Replace part of codes in App.xaml.cs with the following:

protected override async void OnLaunched(Microsoft.UI.Xaml.LaunchActivatedEventArgs args)
{
    // Get the activation args
    var appArgs = Microsoft.Windows.AppLifecycle.AppInstance.GetCurrent().GetActivatedEventArgs();

    // Get or register the main instance
    var mainInstance = Microsoft.Windows.AppLifecycle.AppInstance.FindOrRegisterForKey("main");

    // If the main instance isn't this current instance
    if (!mainInstance.IsCurrent)
    {
        // Redirect activation to that instance
        await mainInstance.RedirectActivationToAsync(appArgs);

        // And exit our instance and stop
        System.Diagnostics.Process.GetCurrentProcess().Kill();
        return;
    }

    // Otherwise, register for activation redirection
    Microsoft.Windows.AppLifecycle.AppInstance.GetCurrent().Activated += App_Activated;

    m_window = new MainWindow();
    m_window.Activate();
}

private Window m_window;

private void App_Activated(object sender, Microsoft.Windows.AppLifecycle.AppActivationArguments e)
{

}

3. Set a breakpoint at if (!mainInstance.IsCurrent) line.
4. F5, then you will see IsCurrent with a true value
5. Launch the app again using the Start Menu icon
6. The IsCurrent value is still true

Expected behavior

It should not launch a second app instance just like the solution from this repo.

Screenshots

NuGet package version

1.0.0

Packaging type

Packaged (MSIX)

Windows version

Windows 11 (22000)

IDE

Visual Studio 2022

Additional context

Tried both .NET 5 and 6, none of them are working. Should not be a Framework related issue.

[andrewleader]

Hey @JohnCido, are you compiling your app for x86? There's a known bug in 1.0.0 where FindOrRegister always just returns your current instance (exactly what you described) as seen in: #1717

We're going to fix that in a 1.0.1 servicing release, but we don't have a plan for when that will be released yet.

First uninstall and then reinstall your app, then try switching it to x64. I'm going to close this bug as a dupe of that, but if switching to x64 doesn't fix your issue, you can reopen!

[JohnCido]

Hey @JohnCido, are you compiling your app for x86? There's a known bug in 1.0.0 where FindOrRegister always just returns your current instance (exactly what you described) as seen in: #1717

We're going to fix that in a 1.0.1 servicing release, but we don't have a plan for when that will be released yet.

First uninstall and then reinstall your app, then try switching it to x64. I'm going to close this bug as a dupe of that, but if switching to x64 doesn't fix your issue, you can reopen!

Oh my god, I finally located the cause of the issue. The actual building target for my x64 configs is actually set to x86 by mistake in the config manager. Now it finally works! I close the related discussion thread too.
Thanks for the help.