Access Violation in WinUI 3

[hez2010]

Describe the bug

We encountered access violation while developing a WinUI 3 app. It happens in the PropertyChanged event for our ColumnsViewModel (we use this ViewModel to provide column properties for ListView).
Given that the failure happens in unmanaged code with 0xC0000005, we think this might be a bug of WinUI 3.

Steps to reproduce the bug

App dump: https://1drv.ms/u/s!ApWNk8G_rszRgooFZijjJphwT7b17g?e=1UowSc

Expected behavior

No crashing is expected.

Screenshots

NuGet package version

WASDK 1.2-preview1

Windows app type

• UWP
• Win32

Device form factor

Desktop

Windows version

Windows Insider Build (25193)

[lukedukeus]

I hit this issue when binding to a property on an interface or abstract class with a treeview

[yaira2]

This issue is blocking us from adopting WinUI 3. @gabbybilka

[MikeHillberg]

Agree it looks like a bug in WinUI3. Thanks for providing the debug info. In response to the property change notification, it's trying to reach back and get the new value, and it looks like the pointer it has to the internal ICustomProperty reflection object is bad.

In the interest of getting unblocked, maybe you could switch this binding to an {x:Bind}, or otherwise add some code to replace it. If it's happening for all of the bindings on this object, then that would be interesting to know too.

[hez2010]

We already use x:Bind where possible but seems that it is still crashing. It's weird that the crash only happens on ListView, if we use a GridView then the crash just disappeared.
This issue has been a release blocker for us (we recently migrated Files from UWP to WinUI 3, and this issue causes random crashes during folder navigation).

[hez2010]

We workarounded the issue by not replacing the whole viewModel but instead changing the properties of the viewModel.
See files-community/Files#10447.

[github-actions]

This issue is stale because it has been open 180 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[hez2010]

To recap this issue, it may happen when you are replacing the existing ViewModel with a new instance of ViewModel and then notify the changes using the PropertyChanged event.

class ParentViewModel : INotifyPropertyChanged
{
    private ChildViewModel _children;
    public ChildViewModel Children
    {
        get => ...
        set
        {
            _children = value;
            PropertyChanged?.Invoke(this, new(nameof(ChildViewModel)));
        }
    }
}

Then bind your page to ParentViewModel and the column definitations of a ListView to Children. You may reproduce it if the Children being replaced frequently.

[yaira2]

@llongley as someone who manages a large repo, I understand the challenge of trying to manage issues and I appreciate everything that's being done to close old issues. Having said that, it's disappointing when issues get closed without having a discussion with the author who took the time to report the issue and keep it active. This doesn't reflect well on WinUI and I hope you reconsider the processes being used to close issues.