NullReferenceException in Android TabbedPageManager

[Mysame]

Description

[AppCenterXamarinCrashes] Unhandled Exception from source=AppDomain
[AppCenterXamarinCrashes] System.NullReferenceException: Object reference not set to an instance of an object.
[AppCenterXamarinCrashes]    at Microsoft.Maui.Controls.Handlers.TabbedPageManager.Listeners.OnPageSelected(Int32 position) in D:\a\_work\1\s\src\Controls\src\Core\Platform\Android\TabbedPageManager.cs:line 843
[AppCenterXamarinCrashes]    at AndroidX.ViewPager2.Widget.ViewPager2.OnPageChangeCallback.n_OnPageSelected_I(IntPtr jnienv, IntPtr native__this, Int32 position) in C:\a\_work\1\s\generated\androidx.viewpager2.viewpager2\obj\Release
et6.0-android\generated\src\AndroidX.ViewPager2.Widget.ViewPager2.cs:line 318
[AppCenterXamarinCrashes]    at Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PPI_V(_JniMarshal_PPI_V callback, IntPtr jnienv, IntPtr klazz, Int32 p0) in /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Android.Runtime/JNINativeWrapper.g.cs:line 59
[mono-rt] [ERROR] FATAL UNHANDLED EXCEPTION: System.NullReferenceException: Object reference not set to an instance of an object.
[mono-rt]    at Microsoft.Maui.Controls.Handlers.TabbedPageManager.Listeners.OnPageSelected(Int32 position) in D:\a\_work\1\s\src\Controls\src\Core\Platform\Android\TabbedPageManager.cs:line 843
[mono-rt]    at AndroidX.ViewPager2.Widget.ViewPager2.OnPageChangeCallback.n_OnPageSelected_I(IntPtr jnienv, IntPtr native__this, Int32 position) in C:\a\_work\1\s\generated\androidx.viewpager2.viewpager2\obj\Release
et6.0-android\generated\src\AndroidX.ViewPager2.Widget.ViewPager2.cs:line 318
[mono-rt]    at Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PPI_V(_JniMarshal_PPI_V callback, IntPtr jnienv, IntPtr klazz, Int32 p0) in /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Android.Runtime/JNINativeWrapper.g.cs:line 59

Randomly happens upon navigating BACK from a page, our app consist of a NavigationPage holding a page that extends Microsoft.Maui.Controls.TabbedPage .

I found #10282 which seems to be this exact issue. Again, it happens sporadically.

Steps to Reproduce

    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class AssignmentTabbedContainer : Microsoft.Maui.Controls.TabbedPage
    {
        public bool IsFirstLoad { get; set; }
        public bool isAttachmentPressed { get; set; }
        public AssignmentTabbedContainer()
        {
            InitializeComponent();
        }
    }

<?xml version="1.0" encoding="utf-8" ?>
<TabbedPage x:Class="Signco.Mobile.MaaS.Maui.Pages.AssignmentTabbedContainer.AssignmentTabbedContainer"
            xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
            xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
            xmlns:shared="clr-namespace:Signco.Mobile.MaaS.Maui.Shared"
            xmlns:android="clr-namespace:Microsoft.Maui.Controls.PlatformConfiguration.AndroidSpecific;assembly=Microsoft.Maui.Controls"
            android:TabbedPage.ToolbarPlacement="Bottom"
            x:DataType="viewModels:TabbedPageViewModel"
            ItemsSource="{Binding Tabs}"
            SelectedItem="{Binding SelectedTab, Mode=TwoWay}">

    <NavigationPage.TitleView>
        <shared:TitleView Title="{Binding Title}" />
    </NavigationPage.TitleView>

    <TabbedPage.ItemTemplate>
        <DataTemplate x:DataType="viewModels:TabContentPageViewModel">
            <ContentPage Title="{Binding Title}"
                         Shell.NavBarIsVisible="false"
                         Content="{Binding Content.Content}"
                         IconImageSource="{Binding Icon}" />
        </DataTemplate>
    </TabbedPage.ItemTemplate>
</TabbedPage>

Navigating "back" can cause this error to happen.

Link to public reproduction project repository

No response

Version with bug

8.0.10 SR3

Is this a regression from previous behavior?

Yes, this used to work in Xamarin.Forms

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

No response

[Mysame]

maui/src/Controls/src/Core/Platform/Android/TabbedPageManager.cs

Line 839 in f267a5c

var Element = _tabbedPageManager.Element;

TabbedPageManager's Element gets checked for null seemingly everywhere, except for in Listener's OnPageSelected
if (_previousPage != Element.CurrentPage)
This being line 843 as referenced by the stacktrace, I can only assume Element is null here.

I'm sorry I can't quite give a repro as of right now, as it is an internal project for a client. However if need be I can deliver it to someone directly.

[dotnet-policy-service]

Hi @Mysame. We have added the "s/needs-repro" label to this issue, which indicates that we require steps and sample code to reproduce the issue before we can take further action. Please try to create a minimal sample project/solution or code samples which reproduce the issue, ideally as a GitHub repo that we can clone. See more details about creating repros here: https://github.com/dotnet/maui/blob/main/.github/repro.md

This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.

[Utkarsh-Gangwar]

we are getting same issue with tabbed page and crash is happening with .netMAUI Microsoft.MAUI.Controls 8.0.7 @rmarinho could you please let us know in which MAUI version this fix going to be released or else please let us know any workaround for this issue.
Thanks in advance