Bug 32897 - [Android, WP8] Modal navigation doesn't work
Summary: [Android, WP8] Modal navigation doesn't work
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 1.5.0
Hardware: PC Windows
: Normal major
Target Milestone: ---
Assignee: E.Z. Hart [MSFT]
Depends on:
Reported: 2015-08-09 15:17 UTC by Sergey Komisarchik
Modified: 2016-02-29 21:53 UTC (History)
8 users (show)

Tags: ac
Is this bug a regression?: ---
Last known good build:

test case (885.00 KB, application/octet-stream)
2015-08-09 15:19 UTC, Sergey Komisarchik
Navigation Page Sample (130.50 KB, application/x-zip-compressed)
2015-09-03 18:58 UTC, Jimmy [MSFT]

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Description Sergey Komisarchik 2015-08-09 15:17:34 UTC
WP8: app crashes on PopModalAsync() with InvalidOperationException
Android: app stops add pages to modal stack after the first PopModalAsync()

Tested in 1.4.4, 1.5.0-pre1

Complete example:

public class App : Application
    public App()
        this.MainPage = new TestPage(1);

public class TestPage : ContentPage
    public TestPage(int id)
        this.Content = new StackLayout()
            VerticalOptions = LayoutOptions.Center,
            HorizontalOptions = LayoutOptions.Center,
            Children = { new Label() { Text = "Page" + id, FontSize = 30 } }

        this.Appearing += async delegate
            await Task.Delay(1000);

            if (id == 1) await this.Navigation.PushModalAsync(new TestPage(id + 1));
            else await this.Navigation.PopModalAsync();
Comment 1 Sergey Komisarchik 2015-08-09 15:19:26 UTC
Created attachment 12422 [details]
test case
Comment 2 Sergey Komisarchik 2015-08-09 15:23:39 UTC
Additional info: in Android case Page1 doesn't invoke Appearing event after Page2 is popped out via PopModalAsync().
Comment 3 Ram Chandra 2015-08-18 13:09:21 UTC
I have checked this issue and with the help of attached project I am able to reproduce this issue.

Case1 : With Windows Phone:
When I deploy the application on windows emulator the application crashes with InvalidOperationException when

Screencast: http://www.screencast.com/t/FRZhOY9hi
Debug Output: https://gist.github.com/Parmendrak/21c79f56cdd1ceeda746
IDE logs: https://gist.github.com/Parmendrak/2890980ab3f0b721cc87

Case2: With Android Phone
After first PopModalAsync() application execution stops.

Debug Output: https://gist.github.com/Parmendrak/13a365782bfc6c87a0ac
IDE logs: https://gist.github.com/Parmendrak/86c57e2de4dc834f9aea

Additional Info: I am not getting the reported behavior on iOS.

Environment Info:


Microsoft Visual Studio Professional 2013
Version 12.0.30723.00 Update 3
Microsoft .NET Framework
Version 4.5.51641

Installed Version: Professional

LightSwitch for Visual Studio 2013   06177-004-0447006-02641
Microsoft LightSwitch for Visual Studio 2013

Team Explorer for Visual Studio 2013   06177-004-0447006-02641
Microsoft Team Explorer for Visual Studio 2013

Visual Basic 2013   06177-004-0447006-02641
Microsoft Visual Basic 2013

Visual C# 2013   06177-004-0447006-02641
Microsoft Visual C# 2013

Visual C++ 2013   06177-004-0447006-02641
Microsoft Visual C++ 2013

Visual F# 2013   06177-004-0447006-02641
Microsoft Visual F# 2013

Visual Studio 2013 Code Analysis Spell Checker   06177-004-0447006-02641
Microsoft® Visual Studio® 2013 Code Analysis Spell Checker

Portions of International CorrectSpell™ spelling correction system © 1993 by Lernout & Hauspie Speech Products N.V. All rights reserved.

The American Heritage® Dictionary of the English Language, Third Edition Copyright © 1992 Houghton Mifflin Company. Electronic version licensed from Lernout & Hauspie Speech Products N.V. All rights reserved.

Windows Phone SDK 8.0 - ENU   06177-004-0447006-02641
Windows Phone SDK 8.0 - ENU

Application Insights Tools for Visual Studio Package   1.0
Application Insights Tools for Visual Studio

ASP.NET and Web Tools   12.3.50717.0
Microsoft Web Developer Tools contains the following components:
Support for creating and opening ASP.NET web projects
Browser Link: A communication channel between Visual Studio and browsers
Editor extensions for HTML, CSS, and JavaScript
Page Inspector: Inspection tool for ASP.NET web projects
Scaffolding: A framework for building and running code generators
Server Explorer extensions for Microsoft Azure Websites
Web publishing: Extensions for publishing ASP.NET web projects to hosting providers, on-premises servers, or Microsoft Azure

ASP.NET Web Frameworks and Tools 2012.2   4.1.21001.0
For additional information, visit http://go.microsoft.com/fwlink/?LinkID=309563

ASP.NET Web Frameworks and Tools 2013   5.2.20703.0
For additional information, visit http://www.asp.net/

Common Azure Tools   1.2
Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.

Microsoft Advertising SDK for Windows Phone   
Microsoft Advertising SDK for Windows Phone

Microsoft Azure Mobile Services Tools   1.2
Microsoft Azure Mobile Services Tools

Multilingual App Toolkit   3.1.1250.0
Multilingual App Toolkit helps you localize your Windows Store app by providing file management, pseudo and machine translation, translation editor, and build integration. http://go.microsoft.com/fwlink?linkid=245767

NuGet Package Manager   2.8.60318.734
NuGet Package Manager in Visual Studio. For more information about NuGet, visit http://docs.nuget.org/.

Office Developer Tools for Visual Studio 2013 ENU   12.0.30626
Microsoft Office Developer Tools for Visual Studio 2013 ENU

PowerShell Tools   1.2
Provides file classification services using PowerShell

PreEmptive Analytics Visualizer   1.2
Microsoft Visual Studio extension to visualize aggregated summaries from the PreEmptive Analytics product.

SQL Server Data Tools   12.0.30919.1
Microsoft SQL Server Data Tools

Windows Phone 8.1 SDK Integration   1.0
This package integrates the tools for the Windows Phone 8.1 SDK into the menus and controls of Visual Studio.

Workflow Manager Tools 1.0   1.0
This package contains the necessary Visual Studio integration components for Workflow Manager.

Xamarin   3.11.836.0 (ed5c750)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.

Xamarin.Android (f98871a95a479f6d71b3067b7e5834d41fcb2118)
Visual Studio plugin to enable development for Xamarin.Android.

Xamarin.Forms Intellisense   1.0
Provides intellisense for Xamarin.Forms in the XML editor.

Xamarin.iOS (6db87c53c073f4af2f5247fb738a27ea08c094fd)
Visual Studio extension to enable development for Xamarin.iOS.

Xamarin.iOS Unified Migration   1.0
Automated migration for Xamarin iOS Classic projects to Unified

Xamarin.TestCloud.Integration   1.0
Early preview of Xamarin Test Cloud integration
Comment 4 Paul DiPietro [MSFT] 2015-08-27 15:42:40 UTC
I'm seeing similar things with, including the TargetInvocationException on WP. iOS seems fine, though.
Comment 5 Jimmy [MSFT] 2015-09-03 18:58:02 UTC
Created attachment 12743 [details]
Navigation Page Sample

I've uploaded a different sample that demonstrates that issue with PopModalAsync() on Windows Phone is made better when MainPage is wrapped in a NavigationPage.

In the original sample project, pushing a modal page and then popping it would result in an InvalidOperationException. However, when App.Current.MainPage is a NavigationPage, PopModalAsync works as expected with a single page in the modal stack.

But if you push another modal page from the first modal page, the app will crash with the same exception when you try to pop the second modal page.

It makes sense that you would need a NavigationPage in order for push/pop to work, however the docs for INavigation indicate:

> "Also note that the Windows Phone platform provides navigation natively. Therefore, you do not need to use a NavigationPage object to get navigation on that platform."
Comment 6 Jon Goldberger [MSFT] 2015-09-11 16:10:42 UTC
Possibly related bug #33829
Comment 7 Jon Goldberger [MSFT] 2015-09-11 16:12:13 UTC
Also possibly related to bug #33714