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.NET MAUI is the .NET Multi-platform App UI, a framework for building native device applications spanning mobile, tablet, and desktop.
https://dot.net/maui
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NullReferenceException when starting application with empty shell on Windows #21562

Open voroninp opened 7 months ago

voroninp commented 7 months ago

Description

Shell requires adding at least one item to it. When I have empty shell and try to deploy it to Android I get legit error:

System.InvalidOperationException: 'Active Shell Item not set. Have you added any Shell Items to your Shell?' image

However, when I do the same for Windows, debugger breaks at UnhandledException handler defined in InitializeComponent method in EmptyShell\EmptyShell\obj\Debug\net8.0-windows10.0.19041.0\win10-x64\Platforms\Windows\App.g.i.cs And event args contain NullReferenceExcepton: image Stacktrace:

at Microsoft.Maui.Controls.Routing.GetRoute(BindableObject obj) at Microsoft.Maui.Controls.Routing.IsImplicit(BindableObject source) at Microsoft.Maui.Controls.Platform.ShellView.SwitchShellItem(ShellItem newItem, Boolean animate) at Microsoft.Maui.Controls.Handlers.ShellHandler.MapCurrentItem(ShellHandler handler, Shell view) at Microsoft.Maui.PropertyMapper2.<>c__DisplayClass5_0.<Add>b__0(IElementHandler h, IElement v) at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView) at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView) at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) at Microsoft.Maui.Handlers.ViewHandler2.SetVirtualView(IView view) at Microsoft.Maui.Controls.Handlers.ShellHandler.SetVirtualView(IView view) at Microsoft.Maui.Handlers.ViewHandler2.SetVirtualView(IElement view) at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value) at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) at Microsoft.Maui.Handlers.WindowHandler.MapContent(IWindowHandler handler, IWindow window) at Microsoft.Maui.PropertyMapper2.<>c__DisplayClass5_0.b__0(IElementHandler h, IElement v) at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView) at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView) at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) at Microsoft.Maui.Platform.ElementExtensions.SetHandler(IWinRTObject nativeElement, IElement element, IMauiContext context) at Microsoft.Maui.Platform.ElementExtensions.SetWindowHandler(Window platformWindow, IWindow window, IMauiContext context) at Microsoft.Maui.Platform.ApplicationExtensions.CreatePlatformWindow(Application platformApplication, IApplication application, OpenWindowRequest args) at Microsoft.Maui.Platform.ApplicationExtensions.CreatePlatformWindow(Application platformApplication, IApplication application, LaunchActivatedEventArgs args) at Microsoft.Maui.MauiWinUIApplication.OnLaunched(LaunchActivatedEventArgs args) at Microsoft.UI.Xaml.Application.Microsoft.UI.Xaml.IApplicationOverrides.OnLaunched(LaunchActivatedEventArgs args) at ABI.Microsoft.UI.Xaml.IApplicationOverrides.Do_Abi_OnLaunched_0(IntPtr thisPtr, IntPtr args)

IMO, it's a bug. Exception should be the same as for Android.

Steps to Reproduce

  1. Create default MAUI project with Shell.
  2. Comment shell's content, so it does not contain items.
  3. Try to run application in Debug mode targeting Windows Machine.
  4. See debugger break at UnhandledException

Link to public reproduction project repository

No response

Version with bug

8.0.3 GA

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

Windows

Affected platform versions

No response

Did you find any workaround?

No Solution: EmptyShell.zip

Relevant log output

No response

RoiChen001 commented 7 months ago

Can repro this issue at Windows platform on the latest 17.10.0 Preview 2.0(8.0.14).