Try the below syntax:
DateTime.ParseExact("my_date_str", {"MMMM yy", "MMMM yyyy"}, System.Globalization.CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.None).ToString("MMM yyyy")
Hope it helps!!
Try the below syntax:
DateTime.ParseExact("my_date_str", {"MMMM yy", "MMMM yyyy"}, System.Globalization.CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.None).ToString("MMM yyyy")
Hope it helps!!