codice:System.NullReferenceException: Riferimento a un oggetto non impostato su un'istanza di oggetto. in System.Windows.Forms.DataGridViewCell.GetEditedFormattedValue(Object value, Int32 rowIndex, DataGridViewCellStyle& dataGridViewCellStyle, DataGridViewDataErrorContexts context) in System.Windows.Forms.DataGridViewCell.PaintWork(Graphics graphics, Rectangle clipBounds, Rectangle cellBounds, Int32 rowIndex, DataGridViewElementStates cellState, DataGridViewCellStyle cellStyle, DataGridViewAdvancedBorderStyle advancedBorderStyle, DataGridViewPaintParts paintParts) in System.Windows.Forms.DataGridViewRow.PaintCells(Graphics graphics, Rectangle clipBounds, Rectangle rowBounds, Int32 rowIndex, DataGridViewElementStates rowState, Boolean isFirstDisplayedRow, Boolean isLastVisibleRow, DataGridViewPaintParts paintParts) in System.Windows.Forms.DataGridViewRow.Paint(Graphics graphics, Rectangle clipBounds, Rectangle rowBounds, Int32 rowIndex, DataGridViewElementStates rowState, Boolean isFirstDisplayedRow, Boolean isLastVisibleRow) in System.Windows.Forms.DataGridView.PaintRows(Graphics g, Rectangle boundingRect, Rectangle clipRect, Boolean singleHorizontalBorderAdded) in System.Windows.Forms.DataGridView.PaintGrid(Graphics g, Rectangle gridBounds, Rectangle clipRect, Boolean singleVerticalBorderAdded, Boolean singleHorizontalBorderAdded) in System.Windows.Forms.DataGridView.OnPaint(PaintEventArgs e) in System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer) in System.Windows.Forms.Control.WmPaint(Message& m) in System.Windows.Forms.Control.WndProc(Message& m) in System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)