The following test failed in the JDK21 CI:

java/text/Format/DateFormat/DateFormatRegression.java

Here's a snippet from the log file:

#section:main
----------messages:(6/323)----------
command: main -Djava.locale.providers=COMPAT,SPI DateFormatRegression
reason: User specified action: run main/othervm -Djava.locale.providers=COMPAT,SPI DateFormatRegression 
started: Tue Apr 11 15:21:13 UTC 2023
Mode: othervm [/othervm specified]
finished: Tue Apr 11 15:21:14 UTC 2023
elapsed time (seconds): 0.321
----------configuration:(0/0)----------
----------System.out:(3/99)----------
DateFormatRegression {
  Test4089106 {
    Uncaught exception thrown in test method Test4089106
----------System.err:(14/854)----------
java.lang.RuntimeException: Uncaught exception thrown in test method Test4089106
	at IntlTest.errImpl(IntlTest.java:198)
	at IntlTest.errln(IntlTest.java:185)
	at IntlTest.run(IntlTest.java:126)
	at DateFormatRegression.main(DateFormatRegression.java:40)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:578)
	at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:125)
	at java.base/java.lang.Thread.run(Thread.java:1592)

JavaTest Message: Test threw exception: java.lang.RuntimeException: Uncaught exception thrown in test method Test4089106
JavaTest Message: shutting down test


Hidden by the test class, the real exception thrown is:

Caused by: java.time.zone.ZoneRulesException: Unknown time-zone ID: FAKEZONE
        at java.base/java.time.zone.ZoneRulesProvider.getProvider(ZoneRulesProvider.java:281)
        at java.base/java.time.zone.ZoneRulesProvider.getRules(ZoneRulesProvider.java:236)
        at java.base/java.time.ZoneRegion.ofId(ZoneRegion.java:121)
        at java.base/java.time.ZoneId.of(ZoneId.java:411)
        at java.base/java.time.ZoneId.of(ZoneId.java:359)
        at java.base/java.time.ZoneId.of(ZoneId.java:315)
        at java.base/java.util.TimeZone.toZoneId0(TimeZone.java:605)
        at java.base/java.util.TimeZone.toZoneId(TimeZone.java:582)
        at java.base/java.util.TimeZone.toZoneId0(TimeZone.java:594)
        at java.base/java.util.TimeZone.toZoneId(TimeZone.java:582)
        at java.base/java.time.ZoneId.systemDefault(ZoneId.java:275)
        at java.base/java.time.Clock.systemDefaultZone(Clock.java:185)
        at java.base/java.time.ZonedDateTime.now(ZonedDateTime.java:201)
        at java.base/jdk.internal.logger.SimpleConsoleLogger.format(SimpleConsoleLogger.java:279)
        at java.base/jdk.internal.logger.SimpleConsoleLogger.publish(SimpleConsoleLogger.java:303)
        at java.base/jdk.internal.logger.SimpleConsoleLogger.log(SimpleConsoleLogger.java:122)
        at java.base/java.lang.System$Logger.log(System.java:1384)
        at java.base/jdk.internal.logger.AbstractLoggerWrapper.log(AbstractLoggerWrapper.java:73)
        at java.base/sun.util.locale.provider.LocaleProviderAdapter.<clinit>(LocaleProviderAdapter.java:175)