Sub testouille()
With Range("z2:z" & Cells(Rows.Count, "J").End(xlUp).Row)
.NumberFormat = "dd/mm/yyyy"
.FormulaR1C1 = "=IFERROR(DATE(YEAR(RC[-16]),MONTH(RC[-16]),DAY(RC[-16])),"""")"
'.Value = .Value 'débloque si tu ne veux garder que les dates et virer les formules
End With
End Sub