WPF : Dispatcher processing has been suspended, but messages are still being processed

Question

I Have a WPF Project, When i try to Run This Code On RowLoad Event I got below Error :

private void ParentGridView_OnRowLoaded(object sender, EventArgs e)
{
    try
    {
        if(((RadGridView)sender).Columns != null)
        {
            MessageBox.Show(((RadGridView)sender).Columns.Count.ToString(CultureInfo.InvariantCulture));
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

Error : Dispatcher processing has been suspended, but messages are still being processed.

Note That the GridView Control is Telerik RadGridView

Answer 1

This answer describes the same situation as yours. (It references this answer on a different website).

The dispatcher processing is suspended to avoid reentrancy problems when updating the visual tree.

If you really need to display a message box in response to your "Row Loaded" event, you need to defer the call using `Dispatcher.BeginInvoke().

So, replace:

MessageBox.Show(((RadGridView)sender).Columns.Count.ToString(CultureInfo.InvariantCulture));

with:

var msg = ((RadGridView)sender).Columns.Count.ToString(CultureInfo.InvariantCulture);
Dispatcher.BeginInvoke(new Action(() => MessageBox.Show(msg)));

If this code is in a WPF object, then the Dispatcher property is available. Otherwise, you need to get it from somewhere else.