Two ways binding NullReferenceException

Configuration

Name	Version
dotnet tool	5.0.302
target framework	net452, net461, net472

Problem

When I use background binding, provided Path, Source and set mode TwoWay, always throw NullReferenceException , but in net5.0 no exception, but how can i do when in NET Framework?

Whether i use SetBinding or BindingOperations.SetBinding.

StackTrack

   at MS.Internal.AvTrace.AntiFormat(String s)

Code

var q = new Binding();
q.Path = new PropertyPath("RotateTransform");
q.Source = obj.RotateTransformDesigner;
q.Mode = BindingMode.TwoWay;
Bd.SetBinding(Control.RenderTransformProperty, q);
BindingOperations.SetBinding(Bd, Control.RenderTransformProperty, q);//ERROR

[Cricle]

I found!!!

It will given null value!

The code

public class ASetting
    {
        public string Ax { get; set; }
    }
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            var t = new TextBox();
            var data = new ASetting();
            //When I bind control name alway null
            t.SetBinding(NameProperty, new Binding("Ax") { Source = data });
            //I set an error binding, it must throw NullReferenceException
            t.SetBinding(TextBox.AcceptsReturnProperty, new Binding
            {
                Source = data,
                Path=new PropertyPath("aaa")
            });
        }
    }

@singhashish-wpf @miloush @SamBent @lindexi

[Cricle]

@Cricle Please attach a full repro, and more of the stack trace. Also a crash dump, if possible.

AvTrace.AntiFormat in the stack trace suggests that someone is trying to print an error message to the trace output sink (typically the VS output window). Does this happen in .NET 5.0?

A null-reference error suggests that the error message is null. This shouldn’t happen, but perhaps something is wrong with your installation of .NET Framework, maybe the error message lookup fails because of a localization problem. A crash dump might shed light on this; the XAML and code-behind is definitely not enough.

I’m sorry that the original project can’t be provided, but I’m trying to write a sample. Please wait me some days. Thanks.

The StackTrace is here

VS show error line

designUnits.Add(unit);//ERROR

designUnits type is ObservableCollection<T> , unit is a normal clr object, but it contains a Bound instance and a UIElement properties.

VS Version VS 2019 Communtity 16.10.4