Private Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) _
  Handles Button2.Click
        cDateiCopy.isCancel = True
        cWriteFile.isCancel = True
End Sub

        ......
        _daDiag.Fill(_dtDiag)
        prgStatus.Minimum = 1
        prgStatus.Maximum = _dtDiag.Rows.Count
        writer = File.CreateText(Quartal & "\kbvges.txt")
        Dim zeile As Integer = 0
 
        For Each cRow In _dtPat.Rows
            If isCancel = True Then
                writer.Close()
                Kill(Quartal & "\kbvges.txt")
                Exit Function
            End If
            zeile += 1
            prgStatus.Value = zeile
            ......