Unhandled Win32 exception when CollectionViewSource.Source is set via GetVirtualizedFilesVector() WinUI 1.6

[Ponant]

Describe the bug

I am porting a UWP app that heavily uses the FileInformationFactory.GetVirtualizedFilesVector() set to a CollectionViewSource and bound to GridView and other UserControls. The app has been working really well for 4 years now, and I decided to port it to WinUI 1.6 given that UWP seems to be being progressively abandonned.

Therefore, I really hope someone could help me on how I can get this code to work on WinUI or advise me to wait otherwise. This app is farily complex so I would like to avoid working on the upgrade if I know that the FileInformationFactory or the CollectionViewSource is not supported (for instance)

I narrowed down the crash to the following. Create a blank WinUI 1.6 App, Setup the code to pick a folder (code not shown but taken from the docs on WinUI. The FolderPicker returns a StorageFolder, named Folder, successfully, and then run the following simple code on the main thread:

 var queryOptions = new QueryOptions() { FolderDepth = FolderDepth.Deep };
 var query = Folder.CreateFileQueryWithOptions(queryOptions);

 var fileInfoVectors =
     new FileInformationFactory(query, ThumbnailMode.SingleItem, 192,
     ThumbnailOptions.UseCurrentScale, delayLoad: false).GetVirtualizedFilesVector();

 var collectionViewSource = new CollectionViewSource()
 {
     Source = fileInfoVectors
 };

In debug mode, Visual Sutio will throw an unhandled Win32 Exception. The reason is Source = fileInfoVectors with the option FolderDepth.Deep.

Question 1

Is this expected for WinUI 1.6 and any plan to have CollectionViewSource and/Or the FileInformatinFactory fully supported?

Question 2

What is the workaround, knowing that I will not use await Folder.GetFilesAsync() or FileInformation.GetFilesAsync(); as they are extremally slow and consume memory.

Thank you for any guidance.

Steps to reproduce the bug

Exectue the code above in a blank app after having picked a folder named here Folder

Expected behavior

Should not throw.

Screenshots

No response

NuGet package version

WinUI 3 - Windows App SDK 1.6.5: 1.6.250205002

Windows version

Windows 11 (24H2): Build 26100

Additional context

No response

[lhak]

I can confirm that the code you posted works in a UWP project (also using .net 9), but fails in a WinUI 3 project when using a folder picker. Interestingly, I got it working in the latter case for some of the folders returned by the ApplicationData class. So I guess that this functionality is currently limited to applications running in an app-container.

The crash (access violation) seems to occur in the windows storage code (so in Windows itself). Somebody from Microsoft would have to give a definite answer if this is a general issue and if there is any workaround.

[Ponant]

@lhak good find (access violation), I did not think of that.