Object of type 'System.Windows.Data.Binding' cannot be converted to type 'System.Nullable`1[System.Guid]'

Question

Similar problem to what's asked here , but it looks like the cause of this exception in this case is different. Perhaps I've set up my property wrong?

I've got a custom usercontrol, which I want to bind to. However, InitializeComponent throws the error Object of type 'System.Windows.Data.Binding' cannot be converted to type 'System.Nullable 1[System.Guid]' VS says it's the set property that's throwing this error.

I simplified my property to try and find the error, but it still happens without any setter logic

public Guid? SelectedItemGUID
{
    get
    {
        if (SelectedItem == null) return null;
        else return (Guid)SelectedItem.GetType().GetProperty("GUID").GetValue(SelectedItem, null);
    }
    set
    {
        return;
    }
}

I'm binding to in the XAML using (client.BIllToClient is a Guid? )

SelectedItemGUID="{Binding Path=client.BillToClient, Mode=TwoWay}"

Answer 1

Try this

public static readonly DependencyProperty SelectedItemGUIDProperty = DependencyProperty.Register("SelectedItemGUID",typeof(Guid?),typeof(UserControl),new FrameworkPropertyMetadata(null));

    public Guid? SelectedItemGUID
    {
        public Guid? SelectedItemGUID
    {
        get { return (Guid?)GetValue(SelectedItemGUIDProperty); }
        set { SetValue(SelectedItemGUIDProperty, (Guid?)SelectedItem.GetType().GetProperty("GUID").GetValue(SelectedItem, null)); }
    }
    }

I think you are trying to Bind simple CLR property . Binding require Target as DependencyProperty Custom binding .I have typeof(UserControl) as parent type in above code replace it with the Type of your control.