Public Function GetCellErrorText( _
   ByVal rowIndex As Integer, _
   ByVal columnIndex As Integer _
) As String

Dim instance As SheetView
Dim rowIndex As Integer
Dim columnIndex As Integer
Dim value As String
 
value = instance.GetCellErrorText(rowIndex, columnIndex)

public string GetCellErrorText( 
   int rowIndex,
   int columnIndex
)

fpSpread1.ShowCellErrors = true;
fpSpread1.Sheets[0].Cells[1, 1].ErrorText = "CellError";
fpSpread1.Sheets[0].Cells[1, 1].Locked = true;

private void button1_Click(object sender, EventArgs e)
        {
            listBox1.Items.Add(fpSpread1.Sheets[0].GetCellErrorText(1, 1).ToString());           
        }

FpSpread1.ShowCellErrors = True
FpSpread1.Sheets(0).Cells(1, 1).ErrorText = "CellError"
FpSpread1.Sheets(0).Cells(1, 1).Locked = True

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        ListBox1.Items.Add(FpSpread1.Sheets(0).GetCellErrorText(1, 1).ToString())
End Sub