Crash parsing date strings but only on some iOS devices

Most of the iPhone devices and actual users that I have are working fine. But when I check the crash log in Xcode, I get an error that string_date is nil on only some devices.

Code_1 is a code that is modified because code_2 is said to be nil.

code_1:

let timeZone = TimeZone(identifier: "Asia/Seoul")let dateComponents = DateComponents(timeZone: timeZone, year: 2000, month: 01, day: 01,hour: 00,minute: 00,second: 00)let Formatter = DateFormatter()Formatter.timeZone = TimeZone(identifier: "Asia/Seoul")Formatter.dateFormat = "yyyyMMdd HHmmss"let Date_1 = Calendar.current.date(from: dateComponents)let string_date = Formatter.string(from:Date_1!)let final_Date = Formatter.date(from: string_date) // <- Swift runtime failure: Unexpectedly found nil while unwrapping an Optional value

code_2:

let date_string: String = "20000101 000000"let Formatter = DateFormatter()Formatter.dateFormat = "yyyyMMdd HHmmss"//Formatter.timeZone = NSTimeZone(name: "KST") as TimeZone?Formatter.locale = NSLocale(localeIdentifier: "ko_KR") as Localelet stringDate = Formatter.date(from: date_string) //<- Swift runtime failure: Unexpectedly found nil while unwrapping an Optional value

Code that sets the date to 2000-01-01/00:00:00:00 so that a certain result value is obtained on all iPhone phones.