Support navigating to a new shell via NavigationPage

[gianox]

Description

I make a NavigationPage that navigates to a Shell. When I press the back button on my Android device, it crashes the app. It works on Windows.

Steps to Reproduce

1. Create a new .NET Maui app

2. Create a ContentPage with a button to navigate to a new AppShell

3. Change the App.cs to this:
   public App()
   {
   InitializeComponent();

        MainPage = new NavigationPage(new ContentPageExample());
    }
   

4. Now, when the app starts in the ContentPage, you can navigate to the Shell. But when you press back on Android, it crashes. With Windows it works.

Link to public reproduction project repository

https://github.com/gianox/MauiShellNavCrash

Version with bug

8.0.61 SR6.1

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

Android

Affected platform versions

No response

Did you find any workaround?

No response

Relevant log output

0xFFFFFFFFFFFFFFFF in Android.Runtime.RuntimeNativeMethods.monodroid_debugger_unhandled_exception	C#
 	0x1A in Android.Runtime.JNINativeWrapper._unhandled_exception at /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Android.Runtime/JNINativeWrapper.g.cs:12,5	C#
 	0x1D in Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PP_V at /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Android.Runtime/JNINativeWrapper.g.cs:23,26	C#
 	0x63 in Microsoft.Maui.Controls.Platform.Compatibility.ShellToolbarTracker.Dispose at D:\a\_work\1\s\src\Controls\src\Core\Compatibility\Handlers\Shell\Android\ShellToolbarTracker.cs:183,5	C#
 	0x2 in Java.Lang.Object.Java.Interop.IJavaPeerable.Disposed at /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Java.Lang/Object.cs:179,4	C#
 	0x39 in Java.Interop.JniRuntime.JniValueManager.DisposePeer at /Users/runner/work/1/s/xamarin-android/external/Java.Interop/src/Java.Interop/Java.Interop/JniRuntime.JniValueManager.cs:151,5	C#
 	0xB in Java.Lang.Object.Dispose at /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Java.Lang/Object.cs:211,4	C#
 	0x94 in Microsoft.Maui.Controls.Platform.Compatibility.ShellSectionRenderer.Destroy at D:\a\_work\1\s\src\Controls\src\Core\Compatibility\Handlers\Shell\Android\ShellSectionRenderer.cs:186,5	C#
 	0x1 in Microsoft.Maui.Controls.Platform.Compatibility.ShellSectionRenderer.OnDestroy at D:\a\_work\1\s\src\Controls\src\Core\Compatibility\Handlers\Shell\Android\ShellSectionRenderer.cs:207,4	C#
 	0x8 in AndroidX.Fragment.App.Fragment.n_OnDestroy at C:\a\_work\1\s\generated\androidx.fragment.fragment\obj\Release\net6.0-android\generated\src\AndroidX.Fragment.App.Fragment.cs:2067,4	C#
 	0x8 in Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PP_V at /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Android.Runtime/JNINativeWrapper.g.cs:22,5	C#

[github-actions[bot]]

Hi I'm an AI powered bot that finds similar issues based off the issue title.

Please view the issues below to see if they solve your problem, and if the issue describes your problem please consider closing this one and thumbs upping the other issue to help us prioritize it. Thank you!

Open similar issues:

• App crashes when navigating after the app has been in the background (#12553), similarity score: 0.80
• App crashes when navigating from TabbedPage to another TabbedPage (#22131), similarity score: 0.79

Closed similar issues:

• Android crash on navigate back from tab 2 without Shell (#15687), similarity score: 0.84
• Shell Absolute Navigation Crashes when a title view is set to each shell page. (#5944), similarity score: 0.80
• AppShell crashed on Android with "No view found for id 0x1 (unknown) for fragment ShellItemRenderer..." (#7940), similarity score: 0.79

Note: You can give me feedback by thumbs upping or thumbs downing this comment.

[Zhanglirong-Winnie]

This issue has been verified using Visual Studio 17.11.0 Preview 2.1(8.0.61 & 8.0.40). Can repro on Android platform.

[PureWeen]

Currently shell only really supports being the root page and you can only have one shell

We should throw better exception messages to make the platforms consistent.

[gianox]

Use case is there. Bug is only present on specific platform. I think converting it from a bug report into a topic for discussion is the wrong way to actually getting further with the software

[acaliaro]

To date the only way to switch to a new Shell is to assign it to the MainPage, but there are Memory Leak problems

#22645