Xamarin Forms MasterDetail page navigation causing crash on android [Fatal signal 6 (SIGABRT), code -6], Works on iOS and UWP

Question

I have a Master Detail like below

public partial class LeaguesMDPage : MasterDetailPage
{
    public LeaguesMDPage()
    {
        InitializeComponent();
        Master = new LeaguesPage();
        Detail = new NavigationPage(new DivisionsPage(new League()));
    }
}

League Page (the Master) design has a list view like below

    <ListView
    ItemsSource="{Binding Leagues}"
    SelectedItem="{Binding SelectedLeague, Mode=TwoWay}"
    IsPullToRefreshEnabled="True"
    RefreshCommand="{Binding UpdateLeagues}"
    IsRefreshing="{Binding IsBusy}"
    >

and the code behind is

public partial class LeaguesPage : ContentPage
{
    LeaguesViewModel vm;

    public LeaguesPage()
    {
        InitializeComponent();
        BindingContext = vm = new LeaguesViewModel(this);
    }
    protected override void OnAppearing()
    {
        base.OnAppearing();
        vm.UpdateLeagues.Execute(false);   
    }
}

In the LeaguesViewModel I have the the SelectedLeague property setter update the Detail page and hide the Master like so

League _SelectedLeague;

public League SelectedLeague
{
    get { return _SelectedLeague; }
    set
    {
        _SelectedLeague = value;
        OnPropertyChanged();
        if (_SelectedLeague != null)
        {
            Debug.WriteLine($"Navigating to DivisionsPage with LeagueID {_SelectedLeague.ID}");
            var mdp = (MasterDetailPage)App.Current.MainPage;
            Device.OnPlatform(                     
                    Android: () => { mdp.IsPresented = false; },
                    iOS: () => { mdp.IsPresented = false; },
                    WinPhone: () => { },
                    Default: () => { mdp.IsPresented = false; }
                );
            mdp.Detail = new NavigationPage(new DivisionsPage(_SelectedLeague));
            _SelectedLeague = null;
        }
    }
}

This does seems to work as I hope sometimes. It Navigates to the new DivisionsPage and hides the master. Seems to work fine on iOS and UWP, but its crashing on Android with the following

[0:] Server Returned 34 divisions
[0:] Navigating to DivisionsPage with LeagueID 12
[0:] UpdatePoolRankings: Called GetDivisionsAsync
03-23 02:40:52.151 W/Mono    ( 6249): The request to load the assembly System.Core v4.0.0.0 was remapped to v2.0.5.0
03-23 02:40:52.151 D/Mono    ( 6249): Unloading image System.Core.dll [0x99db7700].
03-23 02:40:52.151 D/Mono    ( 6249): Image addref System.Core[0xaec169a0] -> System.Core.dll[0x9d166d00]: 11
03-23 02:40:52.151 D/Mono    ( 6249): Config attempting to parse: 'System.Core.dll.config'.
03-23 02:40:52.151 D/Mono    ( 6249): Config attempting to parse: '/Users/builder/data/lanes/4009/f3074d2c/source/monodroid/builds/install/mono-x86/etc/mono/assemblies/System.Core/System.Core.config'.
03-23 02:40:52.152 W/Mono    ( 6249): The request to load the assembly System.Core v4.0.0.0 was remapped to v2.0.5.0
03-23 02:40:52.152 D/Mono    ( 6249): Unloading image System.Core.dll [0x99db7700].
03-23 02:40:52.152 D/Mono    ( 6249): Image addref System.Core[0xaec169a0] -> System.Core.dll[0x9d166d00]: 12
03-23 02:40:52.152 D/Mono    ( 6249): Config attempting to parse: 'System.Core.dll.config'.
03-23 02:40:52.152 D/Mono    ( 6249): Config attempting to parse: '/Users/builder/data/lanes/4009/f3074d2c/source/monodroid/builds/install/mono-x86/etc/mono/assemblies/System.Core/System.Core.config'.
03-23 02:40:52.383 D/Mono    ( 6249): [0x9b5bf930] hill climbing, change max number of threads 4
[0:] Server Returned 3 divisions
03-23 02:40:52.421 F/        ( 6249): * Assertion at /Users/builder/data/lanes/4009/f3074d2c/source/mono/mono/metadata/sgen-tarjan-bridge.c:1139, condition `xref_count == xref_index' not met
03-23 02:40:52.421 F/libc    ( 6249): Fatal signal 6 (SIGABRT), code -6 in tid 6249 (ClubApp.Droid)
InspectorDebugSession(21): Disposed
InspectorDebugSession(21): HandleTargetEvent: TargetExited

Please let me know if more details are need, thanks!

Answer 1

I updated your sample to the latest release of 2.3.4 and it runs on Android without an issue. I would suggest that you remove the code behind in your MasterDetailPage and update it to the following:

<?xml version="1.0" encoding="utf-8" ?>
<MasterDetailPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:ClubApp.Views;assembly=ClubApp"
             xmlns:model="clr-namespace:ClubApp.Models;assembly=ClubApp"
             x:Class="ClubApp.Views.MainMasterDetailPage" 
             Title="MD Page"
             IsPresented="True">
    <MasterDetailPage.Master>
        <local:LeaguesPage />
    </MasterDetailPage.Master>
    <MasterDetailPage.Detail>
        <NavigationPage>
            <x:Arguments>
                <local:DivisionsPage>
                    <x:Arguments>
                        <model:League />
                    </x:Arguments>
                </local:DivisionsPage>
            </x:Arguments>
        </NavigationPage>
    </MasterDetailPage.Detail>
</MasterDetailPage>

Answer 2

I had a similar problem which turned out to be caused by a bug in the android renderer for the NavigationPage. Check out this thread at the Xamarin Forum there is a linked bug report and a workaround. The issue should be fixed in the current XamForms version.

You could try to leave out the NavigationPage (and set your DivisionsPage directly as the Detail) to find out if it's the NavigationPage which causes the crash.