Bug 40502 - CarouselView NRE on MainPage change WinRT
Summary: CarouselView NRE on MainPage change WinRT
Status: RESOLVED NOT_ON_ROADMAP
Alias: None
Product: Forms
Classification: Xamarin
Component: Windows ()
Version: 2.2.0
Hardware: PC Windows
: Normal normal
Target Milestone: ---
Assignee: Chris King
URL:
Depends on:
Blocks:
 
Reported: 2016-04-19 03:32 UTC by Adam
Modified: 2017-05-05 17:37 UTC (History)
5 users (show)

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


Attachments
Sample Repro (467.68 KB, application/x-zip-compressed)
2016-04-19 03:32 UTC, Adam
Details


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Status:
RESOLVED NOT_ON_ROADMAP

Description Adam 2016-04-19 03:32:46 UTC
Created attachment 15760 [details]
Sample Repro

2.2.0-pre2

If I have a CarouselView on a Page, then I set the MainPage of the app to something different, I will get the below error on WinRT.

   at Xamarin.Forms.Platform.WinRT.CarouselViewRenderer.OnElementChanged(ElementChangedEventArgs`1 e)
   at Xamarin.Forms.Platform.WinRT.VisualElementRenderer`2.SetElement(VisualElement element)
   at Xamarin.Forms.Platform.WinRT.VisualElementRenderer`2.Dispose(Boolean disposing)
   at Xamarin.Forms.Platform.WinRT.VisualElementRenderer`2.Dispose()
   at Xamarin.Forms.Platform.WinRT.VisualElementExtensions.Cleanup(VisualElement self)
   at Xamarin.Forms.Platform.WinRT.PageRenderer.Dispose(Boolean disposing)
   at Xamarin.Forms.Platform.WinRT.VisualElementRenderer`2.Dispose()
   at Xamarin.Forms.Platform.WinRT.VisualElementExtensions.Cleanup(VisualElement self)
   at Xamarin.Forms.Platform.WinRT.Platform.<SetCurrent>d__44.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>b__3(Object state)
   at System.Threading.WinRTSynchronizationContext.Invoker.InvokeCore()

Attached sample project. Load it up and press the Test button.
Comment 1 Adam 2016-04-20 06:36:51 UTC
Still occurs in -pre3

Just noting that it all works ok in iOS.
Comment 2 Adam 2016-04-21 00:56:49 UTC
And just from more testing in trying to work around it, even if you go back or forward in a navigation page, it also throws the same error. You can't move away from a page with a CarouselView on it without the crash.
Comment 3 Ernest Williams 2016-04-26 17:02:41 UTC
I have the same issue on UWP in a MasterDetailPage.  The call stack starts out identically.

Object reference not set to an instance of an object.

   at Xamarin.Forms.Platform.UWP.CarouselViewRenderer.OnElementChanged(ElementChangedEventArgs`1 e)
   at Xamarin.Forms.Platform.UWP.VisualElementRenderer`2.SetElement(VisualElement element)
   at Xamarin.Forms.Platform.UWP.VisualElementRenderer`2.Dispose(Boolean disposing)
   at Xamarin.Forms.Platform.UWP.VisualElementRenderer`2.Dispose()
   at Xamarin.Forms.Platform.UWP.VisualElementExtensions.Cleanup(VisualElement self)
   at Xamarin.Forms.Platform.UWP.PageRenderer.Dispose(Boolean disposing)
   at Xamarin.Forms.Platform.UWP.VisualElementRenderer`2.Dispose()
   at Xamarin.Forms.Platform.UWP.MasterDetailPageRenderer.ClearDetail()
   at Xamarin.Forms.Platform.UWP.MasterDetailPageRenderer.UpdateDetail()
   at Xamarin.Forms.Platform.UWP.MasterDetailPageRenderer.OnElementPropertyChanged(Object sender, PropertyChangedEventArgs e)
   at System.ComponentModel.PropertyChangedEventHandler.Invoke(Object sender, PropertyChangedEventArgs e)
   at Xamarin.Forms.BindableObject.OnPropertyChanged(String propertyName)
   at Xamarin.Forms.Element.OnPropertyChanged(String propertyName)
   at Xamarin.Forms.MasterDetailPage.set_Detail(Page value)
   at Emerson.Pages.DashboardMasterDetailPage.NavigateBack(FormBuilder pageHeaderCell)
   at Xamarin.Forms.MessagingCenter.<>c__DisplayClass4_0`1.<Subscribe>b__0(Object sender, Object args)
   at Xamarin.Forms.MessagingCenter.InnerSend(String message, Type senderType, Type argType, Object sender, Object args)
   at Xamarin.Forms.MessagingCenter.Send[TSender](TSender sender, String message)
   at Emerson.Helpers.FormBuilder.<CreateSections>b__4_5()
   at Xamarin.Forms.Command.<>c__DisplayClass3_0.<.ctor>b__0(Object o)
   at Xamarin.Forms.Command.Execute(Object parameter)
   at Xamarin.Forms.TapGestureRecognizer.SendTapped(View sender)
   at Xamarin.Forms.Platform.UWP.VisualElementTracker`2.OnTap(Object sender, TappedRoutedEventArgs e)
Comment 4 Chris King 2017-05-05 17:37:55 UTC
CarouselView to be deprecated and replaced with https://github.com/xamarin/Xamarin.Forms/pull/853