How do i update datagrid itemsource inside celleditending event

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C#

SQL-Server

WPF

below is my code whenever I change value of cell value and then press enter it shows an exception whereas after editing the cell value when I click mouse button it works fine
The exception I get is An unhandled exception of type 'System.ArgumentOutOfRangeException' occurred in PresentationFramework.dll

and the it also goes into breakmode

private void dgOrder_CellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
        {
            DataGrid dc = (DataGrid)sender;
            DataGridRow row1 = e.Row;
            DataRowView row = (DataRowView)dc.SelectedItems[0];
            var value = e.EditingElement as TextBox;

            int row_index = ((DataGrid)sender).ItemContainerGenerator.IndexFromContainer(row1);

            ol.UpdateOrderLine(row[0].ToString(), "Qty", int.Parse(value.Text.ToString()));
            MessageBox.Show(row_index.ToString() + " " + row["PName"] + " " + e.Column.Header.ToString() + " " + value.Text.ToString() + " result: " + result);
            dgOrder.ItemsSource = ol.GetOrderLine().DefaultView;
        }

What I have tried:

when I remove this line dgOrder.ItemsSource = ol.GetOrderLine().DefaultView it works fine, values are updated in the database but datagrid is not updated at that moment