[WPF] Fix for -> System.Windows.Data Error: 4 -> HorizontalContentAlignment and VerticalContentAlignment

WPF_Error_HV_ContentAlignment.md

Fix for debug output errors

Add the follow lines to the file App.xaml in your WPF application

    <!--
        Global fix for
        
        System.Windows.Data Error: 4 :
        Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''.
        BindingExpression:Path=HorizontalContentAlignment; DataItem=null;
        target element is 'ComboBoxItem' (Name='');
        target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')
        
        System.Windows.Data Error: 4 :
        Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''.
        BindingExpression:Path=VerticalContentAlignment; DataItem=null;
        target element is 'ComboBoxItem' (Name='');
        target property is 'VerticalContentAlignment' (type 'VerticalAlignment')
    -->
    
   <Application.Resources>
        <Style TargetType="ComboBoxItem">
            <Setter Property="HorizontalContentAlignment" Value="Left" />
            <Setter Property="VerticalContentAlignment" Value="Center" />
        </Style>
    </Application.Resources>

That worked! Thank you

@derekhearst I am glad that it helped you.

Can you tell me why this error occurs? I used your method to fix the problem, but I don’t know the principle.

@chenjing1294
Hello, its long time ago that I must use this, IMHO possible on

• A empty source
• Empty elements in a source
• The parent control have no defined size (size not set)
• Use of auto-size and the control can determinate the size

Thank you for the fix.

First a big thank you!
This error is strange it complains about a combobox with no name. All my comboboxes has names. All my object has names to make it easier to find where the error is...

I had the same problem with a ListBox and a (temporarily) empty source. For me it was enough to just assign the default style:

<ListBox ItemContainerStyle="{StaticResource {x:Type ListBoxItem}}" .../>

Thanks, this is still a fix as of today (.NET 9). In my case, the exceptions occur when I change the SortDescriptions of a CollectionViewSource at runtime and that makes the application totally unresponsive (the weird thing is it does not happen when the collection is first loaded, only when its sort order is modified).