NRE in CarouselViewController on iOS 15.5 & 16.4

[mypp74]

Description

2025-03-21 22:38:28.494272+0100 Dopnet.YourDive.Maui[49904:537114] Unhandled managed exception: Value cannot be null. (Parameter 'key') (System.ArgumentNullException)
at System.Collections.Generic.Dictionary2[[System.Object, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[Microsoft.Maui.Controls.Handlers.Items.TemplatedCell, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].FindValue(Object key) at System.Collections.Generic.Dictionary2[[System.Object, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[Microsoft.Maui.Controls.Handlers.Items.TemplatedCell, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].TryGetValue(Object key, TemplatedCell& value)
at Microsoft.Maui.Controls.Handlers.Items.ItemsViewController1[[Microsoft.Maui.Controls.CarouselView, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].UpdateTemplatedCell(TemplatedCell cell, NSIndexPath indexPath) at Microsoft.Maui.Controls.Handlers.Items.ItemsViewController1[[Microsoft.Maui.Controls.CarouselView, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].GetCell(UICollectionView collectionView, NSIndexPath indexPath)
at Microsoft.Maui.Controls.Handlers.Items.CarouselViewController.GetCell(UICollectionView collectionView, NSIndexPath indexPath)
at UIKit.UICollectionView.ReloadItems(NSIndexPath[] indexPaths) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/build/dotnet/ios/generated-sources/UIKit/UICollectionView.g.cs:line 753
at Microsoft.Maui.Controls.Handlers.Items.ObservableItemsSource.<>c__DisplayClass45_0.b__0(UICollectionView c)
at Microsoft.Maui.Controls.Handlers.Items.ObservableItemsSource.Update(Action1 update, NotifyCollectionChangedEventArgs args) at Microsoft.Maui.Controls.Handlers.Items.ObservableItemsSource.Replace(NotifyCollectionChangedEventArgs args) at Microsoft.Maui.Controls.Handlers.Items.ObservableItemsSource.CollectionChanged(NotifyCollectionChangedEventArgs args) at Microsoft.Maui.Controls.Handlers.Items.ObservableItemsSource.CollectionChanged(Object sender, NotifyCollectionChangedEventArgs args) at System.Collections.ObjectModel.ObservableCollection1[[Dopnet.YourDive.Services.DiveInfo, Dopnet.YourDive.Services, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].OnCollectionChanged(NotifyCollectionChangedEventArgs e)
at System.Collections.ObjectModel.ObservableCollection1[[Dopnet.YourDive.Services.DiveInfo, Dopnet.YourDive.Services, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].OnCollectionChanged(NotifyCollectionChangedAction action, Object oldItem, Object newItem, Int32 index) at System.Collections.ObjectModel.ObservableCollection1[[Dopnet.YourDive.Services.DiveInfo, Dopnet.YourDive.Services, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].SetItem(Int32 index, DiveInfo item)
at System.Collections.ObjectModel.Collection1[[Dopnet.YourDive.Services.DiveInfo, Dopnet.YourDive.Services, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].set_Item(Int32 index, DiveInfo value) at Dopnet.YourDive.UI.ViewModels.DiveDetailViewModel.UpdateDive(DiveInfo dive) in C:\Users\MarcPERROT\source\repos\YourDive\Dopnet.YourDive.UI.Logic\YourDive.UI.ViewModels\DiveDetailViewModel.cs:line 614 at Dopnet.YourDive.UI.ViewModels.DiveDetailViewModel.OnDiveChanged(Object sender, ChangedEventArgs1 e) in C:\Users\MarcPERROT\source\repos\YourDive\Dopnet.YourDive.UI.Logic\YourDive.UI.ViewModels\DiveDetailViewModel.cs:line 553
at Dopnet.YourDive.UI.ViewModels.ChangedEventSource1[[Dopnet.YourDive.Services.DiveInfo, Dopnet.YourDive.Services, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].Raise(ChangedEventArgs1 e) in C:\Users\MarcPERROT\source\repos\YourDive\Dopnet.YourDive.UI.Logic\YourDive.UI.ViewModels\ChangedEventSource.cs:line 11
at Dopnet.YourDive.UI.ViewModels.IChangedEventSourceExtensions.RaiseUpdate[DiveInfo](IChangedEventSource1 source, String id, DiveInfo value) in C:\Users\MarcPERROT\source\repos\YourDive\Dopnet.YourDive.UI.Logic\YourDive.UI.ViewModels\IChangedEventSourceExtensions.cs:line 62 at Dopnet.YourDive.UI.ViewModels.IChangedEventSourceExtensions.RaiseUpdate(IChangedEventSource1 source, DiveInfo value) in C:\Users\MarcPERROT\source\repos\YourDive\Dopnet.YourDive.UI.Logic\YourDive.UI.ViewModels\IChangedEventSourceExtensions.cs:line 24
at Dopnet.YourDive.UI.ViewModels.StampsRequestViewModel.RequestStampsAsync() in C:\Users\MarcPERROT\source\repos\YourDive\Dopnet.YourDive.UI.Logic\YourDive.UI.ViewModels\StampsRequestViewModel.cs:line 97
at Dopnet.Maui.CommandFactory.<>c__DisplayClass7_0.<b__0>d.MoveNext() in C:\Users\MarcPERROT\source\repos\YourDive\Dopnet.Maui\CommandFactory.cs:line 48
--- End of stack trace from previous location ---
at System.Threading.Tasks.Task.<>c.b__128_0(Object state)
at Foundation.NSAsyncSynchronizationContextDispatcher.Apply() in /Users/builder/azdo/_work/1/s/xamarin-macios/src/Foundation/NSAction.cs:line 179
--- End of stack trace from previous location ---
at ObjCRuntime.Runtime.ThrowException(IntPtr gchandle) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/ObjCRuntime/Runtime.cs:line 2742
at UIKit.UIApplication.UIApplicationMain(Int32 argc, String[] argv, IntPtr principalClassName, IntPtr delegateClassName) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/UIKit/UIApplication.cs:line 64
at UIKit.UIApplication.Main(String[] args, Type principalClass, Type delegateClass) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/UIKit/UIApplication.cs:line 96
at Dopnet.YourDive.Maui.Program.Main(String[] args) in C:\Users\MarcPERROT\source\repos\YourDive\Dopnet.YourDive.Maui\Platforms\iOS\Program.cs:line 13

Steps to Reproduce

CrashCarouselView.zip

Link to public reproduction project repository

No response

Version with bug

9.0.50 SR5

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

No response

Affected platforms

iOS

Affected platform versions

iOS 15.5

Did you find any workaround?

No response

Relevant log output

[malsabi]

I'm also having this exception, it's really unfortunate that this only happens in iOS. This used to be "Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')." and now we are getting this new exception. @PureWeen If there is any workaround please notify us or if there is a proper way for using CollectionView in iOS. I tried dispatching it on UI Thread, tried concurrency but still the exception happens.

[sheiksyedm]

@malsabi Would it be possible for you to share a replication sample for this issue? I'm not sure in which scenario it occurs, making it difficult to reproduce. If you provide a sample, it would be really helpful in tracking the issue more effectively.

[malsabi]

@sheiksyedm Thank you for your reply. I couldn't replicate this issue in another repository, but It still happens in my app and I cannot share for privacy reasons. However I will provide the exception log that I'm getting maybe It can help to figure out the issue.

  at System.Collections.Generic.Dictionary2[[System.Object, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[Microsoft.Maui.Controls.Handlers.Items.TemplatedCell, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].FindValue(Object key)
   at System.Collections.Generic.Dictionary2[[System.Object, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[Microsoft.Maui.Controls.Handlers.Items.TemplatedCell, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].TryGetValue(Object key, TemplatedCell& value)
   at Microsoft.Maui.Controls.Handlers.Items.ItemsViewController1[[Microsoft.Maui.Controls.ReorderableItemsView, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].UpdateTemplatedCell(TemplatedCell cell, NSIndexPath indexPath)
   at Microsoft.Maui.Controls.Handlers.Items.ItemsViewController1[[Microsoft.Maui.Controls.ReorderableItemsView, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].CreateMeasurementCell(NSIndexPath indexPath)
   at Microsoft.Maui.Controls.Handlers.Items.ItemsViewController1[[Microsoft.Maui.Controls.ReorderableItemsView, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].GetPrototypeForIndexPath(NSIndexPath indexPath)
   at Microsoft.Maui.Controls.Handlers.Items.ItemsViewController1[[Microsoft.Maui.Controls.ReorderableItemsView, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].GetPrototype()
   at Microsoft.Maui.Controls.Handlers.Items.ItemsViewLayout.DetermineCellSize()
   at Microsoft.Maui.Controls.Handlers.Items.ListViewLayout.ConstrainTo(CGSize size)
   at Microsoft.Maui.Controls.Handlers.Items.ItemsViewLayout.UpdateConstraints(CGSize size)
   at Microsoft.Maui.Controls.Handlers.Items.ItemsViewController1[[Microsoft.Maui.Controls.ReorderableItemsView, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].ConstrainItemsToBounds()
   at Microsoft.Maui.Controls.Handlers.Items.ItemsViewController1[[Microsoft.Maui.Controls.ReorderableItemsView, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].ViewWillLayoutSubviews()
   at Microsoft.Maui.Controls.Handlers.Items.StructuredItemsViewController1[[Microsoft.Maui.Controls.ReorderableItemsView, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].ViewWillLayoutSubviews()
   at UIKit.UIApplication.UIApplicationMain(Int32 argc, String[] argv, IntPtr principalClassName, IntPtr delegateClassName) in /Users/builder/azdo/_work/5/s/xamarin-macios/src/UIKit/UIApplication.cs:line 61
   at UIKit.UIApplication.Main(String[] args, Type principalClass, Type delegateClass) in /Users/builder/azdo/_work/5/s/xamarin-macios/src/UIKit/UIApplication.cs:line 96