Bug ID: JDK-8273437 java.text.SimpleDateFormat fails to parse 3 letter month 'Sep'

Type: Bug
Component: core-libs
Sub-Component: java.text
Affected Version: 16

Priority: P4
Status: Resolved
Resolution: Duplicate
OS: generic
CPU: generic

Submitted: 2021-09-06
Updated: 2021-09-08
Resolved: 2021-09-08

ADDITIONAL SYSTEM INFORMATION :
I have no reason to think this is in any way platform specific, but my system is:
java.version = 16.0.2  
javafx.runtime.version = 16+8  
os.name = Windows 10  
os.arch = amd64  
os.version = 10.0  

A DESCRIPTION OF THE PROBLEM :
Until JDK 15, SimpleDateFormat would successfully parse date strings including the month September abbreviated as the 3 letters "Sep".
With JDK 16, this now fails with java.text.ParseException: Unparseable dateIt will parse 
September abbreviated as the 4 letters "Sept", but if the date string comes from third party software, for example the "expires" value in the header data for a cookie from a web browser, JDK 16 now fails where JDK 15 worked.
I have confirmed that this is still broken in JDK 17 & 18 early access versions.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Try to parse a date such as "Sat, 03 Sep 2022 15:42:22 GMT" using SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss")

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
java.version = 15
dateString = Sat, 03 Jan 2022 15:42:22 GMT
    date = Mon Jan 03 15:42:22 GMT 2022
    formatted date = Mon, 03 Jan 2022 15:42:22
dateString = Sat, 03 Feb 2022 15:42:22 GMT
    date = Thu Feb 03 15:42:22 GMT 2022
    formatted date = Thu, 03 Feb 2022 15:42:22
dateString = Sat, 03 Mar 2022 15:42:22 GMT
    date = Thu Mar 03 15:42:22 GMT 2022
    formatted date = Thu, 03 Mar 2022 15:42:22
dateString = Sat, 03 Apr 2022 15:42:22 GMT
    date = Sun Apr 03 15:42:22 BST 2022
    formatted date = Sun, 03 Apr 2022 15:42:22
dateString = Sat, 03 May 2022 15:42:22 GMT
    date = Tue May 03 15:42:22 BST 2022
    formatted date = Tue, 03 May 2022 15:42:22
dateString = Sat, 03 Jun 2022 15:42:22 GMT
    date = Fri Jun 03 15:42:22 BST 2022
    formatted date = Fri, 03 Jun 2022 15:42:22
dateString = Sat, 03 Jul 2022 15:42:22 GMT
    date = Sun Jul 03 15:42:22 BST 2022
    formatted date = Sun, 03 Jul 2022 15:42:22
dateString = Sat, 03 Aug 2022 15:42:22 GMT
    date = Wed Aug 03 15:42:22 BST 2022
    formatted date = Wed, 03 Aug 2022 15:42:22
dateString = Sat, 03 Sep 2022 15:42:22 GMT
    date = Sat Sep 03 15:42:22 BST 2022
    formatted date = Sat, 03 Sep 2022 15:42:22
dateString = Sat, 03 Oct 2022 15:42:22 GMT
    date = Mon Oct 03 15:42:22 BST 2022
    formatted date = Mon, 03 Oct 2022 15:42:22
dateString = Sat, 03 Nov 2022 15:42:22 GMT
    date = Thu Nov 03 15:42:22 GMT 2022
    formatted date = Thu, 03 Nov 2022 15:42:22
dateString = Sat, 03 Dec 2022 15:42:22 GMT
    date = Sat Dec 03 15:42:22 GMT 2022
    formatted date = Sat, 03 Dec 2022 15:42:22
dateString = Sat, 03 Sept 2022 15:42:22 GMT
    java.text.ParseException: Unparseable date: "Sat, 03 Sept 2022 15:42:22 GMT"
ACTUAL -
java.version = 16.0.2
dateString = Sat, 03 Jan 2022 15:42:22 GMT
    date = Mon Jan 03 15:42:22 GMT 2022
    formatted date = Mon, 03 Jan 2022 15:42:22
dateString = Sat, 03 Feb 2022 15:42:22 GMT
    date = Thu Feb 03 15:42:22 GMT 2022
    formatted date = Thu, 03 Feb 2022 15:42:22
dateString = Sat, 03 Mar 2022 15:42:22 GMT
    date = Thu Mar 03 15:42:22 GMT 2022
    formatted date = Thu, 03 Mar 2022 15:42:22
dateString = Sat, 03 Apr 2022 15:42:22 GMT
    date = Sun Apr 03 15:42:22 BST 2022
    formatted date = Sun, 03 Apr 2022 15:42:22
dateString = Sat, 03 May 2022 15:42:22 GMT
    date = Tue May 03 15:42:22 BST 2022
    formatted date = Tue, 03 May 2022 15:42:22
dateString = Sat, 03 Jun 2022 15:42:22 GMT
    date = Fri Jun 03 15:42:22 BST 2022
    formatted date = Fri, 03 Jun 2022 15:42:22
dateString = Sat, 03 Jul 2022 15:42:22 GMT
    date = Sun Jul 03 15:42:22 BST 2022
    formatted date = Sun, 03 Jul 2022 15:42:22
dateString = Sat, 03 Aug 2022 15:42:22 GMT
    date = Wed Aug 03 15:42:22 BST 2022
    formatted date = Wed, 03 Aug 2022 15:42:22
dateString = Sat, 03 Sep 2022 15:42:22 GMT
    java.text.ParseException: Unparseable date: "Sat, 03 Sep 2022 15:42:22 GMT"
dateString = Sat, 03 Oct 2022 15:42:22 GMT
    date = Mon Oct 03 15:42:22 BST 2022
    formatted date = Mon, 03 Oct 2022 15:42:22
dateString = Sat, 03 Nov 2022 15:42:22 GMT
    date = Thu Nov 03 15:42:22 GMT 2022
    formatted date = Thu, 03 Nov 2022 15:42:22
dateString = Sat, 03 Dec 2022 15:42:22 GMT
    date = Sat Dec 03 15:42:22 GMT 2022
    formatted date = Sat, 03 Dec 2022 15:42:22
dateString = Sat, 03 Sept 2022 15:42:22 GMT
    date = Sat Sep 03 15:42:22 BST 2022
    formatted date = Sat, 03 Sept 2022 15:42:22

Full stack trace:
java.text.ParseException: Unparseable date: "Sat, 03 Sep 2022 15:42:22 GMT"
	at java.base/java.text.DateFormat.parse(DateFormat.java:396)
	at dateparsingbug.DateParsingBug.main(DateParsingBug.java:38)

---------- BEGIN SOURCE ----------

import java.text.SimpleDateFormat;
import java.util.Date;

public class DateParsingBug {

	/**
	 * @param args the command line arguments
	 */
	public static void main(String[] args) {
		SimpleDateFormat TEST_DATE_AND_TIME_FORMAT = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss");
		String[] monthNames = {
			"Jan",
			"Feb",
			"Mar",
			"Apr",
			"May",
			"Jun",
			"Jul",
			"Aug",
			"Sep",
			"Oct",
			"Nov",
			"Dec",
			"Sept"
		};
		
		System.out.println("java.version = " + System.getProperty("java.version"));
		for (String monthName: monthNames) {
			try {
				String dateString = "Sat, 03 " + monthName + " 2022 15:42:22 GMT";
				System.out.println("dateString = " + dateString);
				Date date = TEST_DATE_AND_TIME_FORMAT.parse(dateString);
				System.out.println("    date = " + date);
				System.out.println("    formatted date = " + TEST_DATE_AND_TIME_FORMAT.format(date));
			} catch (Exception ex) {
				System.out.println("    " + ex);
			}
		}
	}
}
---------- END SOURCE ----------

FREQUENCY : always

Closed as a dup of JDK-8256837.
08-09-2021
The submitter confirms that the test was run under en-GB.
08-09-2021
Requested the above information from the submitter.
08-09-2021
Possibly the duplicate of JDK-8256837. Can the submitter confirm that the test was run under non-US locale, such as en-GB?
07-09-2021
To get the proper format, assign the Locale by the following code: new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss", Locale.US); The observations on Windows 10: JDK 8: Passed, the output is as expected. JDK 11: Passed. JDK 15: Passed. JDK 16: Passed. This incident can be closed as not an issue. Moved to JDK for further evaluations.
07-09-2021