WPF Recursive call to Automation Peer API is not valid

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I am receiving an error message "Recursive call to Automation Peer API is not valid" when loading a datagrid with a datatemplatecolumn containing a combobox column. The error ends up caught in our unhandled exception code. This seems to be an issue on my machine, and google has provided no source of guidance on resolving the issue. The issue appears to only occur when I am populating the comboboxes with data. Populating the comboboxes (if I do not load data) works correctly, and while the error is displayed I am able to see the data properly retrieved in the background.

I am using a WPF datagrid where I'm using a DataGridTemplateColumn for adding a combobox inside the grid. I have the drop down list bound to an enum using an objectdataprovider. In the code behind when initializing my screen I use a Linq2Sql statement to retrieve data and populate the Itemssource of the grid.

<grid:DataGrid.Resources>
 <ObjectDataProvider
  x:Key="ChangeTypeData"
  MethodName="GetValues"
  ObjectType="{x:Type System:Enum}">
  <ObjectDataProvider.MethodParameters>
   <x:Type TypeName="namespace:ChangeType" />
  </ObjectDataProvider.MethodParameters>
 </ObjectDataProvider>     
    </grid:DataGrid.Resources>

 <grid:DataGrid.Columns>
 <grid:DataGridTextColumn Binding="{Binding DatapointName}" Header="Datapoint Changed" IsReadOnly="True" Width="Auto" />
 <grid:DataGridTemplateColumn Header="Change Type">
  <grid:DataGridTemplateColumn.CellTemplate>
   <DataTemplate>
    <ComboBox
     Text="{Binding Path=ChangeTypeName}"
     ItemsSource="{Binding Source={StaticResource ChangeTypeData}}"
     Name="dgcboChangeType"
SelectionChanged="dgcboChangeType_SelectionChanged"/>
   </DataTemplate>
  </grid:DataGridTemplateColumn.CellTemplate>

Any and all guidance on solving this issue is appreciated.

combobox recursion exception automation wpf
8 Answers

I was able to fix this issue by replacing both the DataGrid and the ComboBox in the WPF XAML file with the following two derived classes which both override the OnCreateAutomationPeer() method.

public class SafeDataGrid : DataGrid
{
    protected override AutomationPeer OnCreateAutomationPeer()
    {
        return null;
    }
}

public class SafeComboBox : ComboBox
{
    protected override AutomationPeer OnCreateAutomationPeer()
    {
        return null;
    }
}
user_61265600

I had this same problem crop up on an older solution (although it was working fine on my local dev computer, but failing on the test system (with WPFToolkit 3.5.50211.1)

Turned out my local dev computer had an older WPFToolkit: 3.5.40128.1

However I did a little more checking around and realised that the problem was only when the DataGrid was a Microsoft.Windows.Controls.DataGrid (ie a WPFToolkit one), and it contained a control from the System.Windows.Controls namespace (in this case a ComboBox) - and from the .Net PresentationFramework.dll )

We'd updated the solution to .Net 4.7.1 from .Net 4.5.1 -> which would have meant a new version of the PresentationFramework.dll, but the WPFToolkit dll had not changed.

Decided that the best way to fix this was to just remove the WPFToolkit.dll reference, and update all the DataGrids from Microsoft.Windows.Controls.DataGrid to the newer System.Windows.Controls.Datagrid.

user_24631200
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