[Native Image] Localized data/time data not working in native image

[Eng-Fouad]

Describe the Issue

Given this sample:

final var ARABIC_GREGORIAN_DATE_FORMATTER = DateTimeFormatter.ofPattern("EEEE dd\\MM\\yyyy G").localizedBy(Locale.forLanguageTag("ar"));
final var ENGLISH_GREGORIAN_DATE_FORMATTER = DateTimeFormatter.ofPattern("EEEE dd/MM/yyyy G").localizedBy(Locale.ENGLISH);

var now = Instant.now();
String arabicGregorianDate = ARABIC_GREGORIAN_DATE_FORMATTER.format(now.atZone(ZoneId.systemDefault()));
String englishGregorianDate = ENGLISH_GREGORIAN_DATE_FORMATTER.format(now.atZone(ZoneId.systemDefault()));

Log.info("arabicGregorianDate = " + arabicGregorianDate);
Log.info("englishGregorianDate = " + englishGregorianDate);

When running in JVM mode, I get this output:

arabicGregorianDate = السبت 18\10\2025 م
englishGregorianDate = Saturday 18/10/2025 AD

However, when I compile it to GraalVM native-image and run it, I get this output:

arabicGregorianDate = Sat 18\10\2025 CE
englishGregorianDate = Saturday 18/10/2025 AD

Notice that Arabic word for Saturday السبت is fallbacked to Sat and م to CE?

I am using -H:IncludeLocales=ar,en as well.

I added the option -H:+TraceLocalizationFeature and I noticed the resource bundle sun.text.resources.cldr.FormatData with locale ar is included in native image (but does not work):

Adding bundle sun.util.resources.cldr.CalendarData, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.CurrencyNames, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.LocaleNames, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.TimeZoneNames, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.cldr.FormatData, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.cldr.FormatData, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.CalendarData, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.CurrencyNames, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.LocaleNames, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.TimeZoneNames, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.cldr.FormatData, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.cldr.FormatData, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.CalendarData, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.CurrencyNames, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.LocaleNames, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.TimeZoneNames, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.cldr.FormatData, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.cldr.FormatData, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.CalendarData, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.CurrencyNames, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.LocaleNames, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.cldr.TimeZoneNames, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.cldr.FormatData, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.cldr.FormatData, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.CalendarData, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.CurrencyNames, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.LocaleNames, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.TimeZoneNames, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.BreakIteratorInfo, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.BreakIteratorResources, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.CollationData, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.FormatData, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.FormatData, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.CalendarData, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.CurrencyNames, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.LocaleNames, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.TimeZoneNames, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.BreakIteratorInfo, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.BreakIteratorResources, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.CollationData, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.FormatData, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.FormatData, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.CalendarData, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.CurrencyNames, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.LocaleNames, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.TimeZoneNames, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.BreakIteratorInfo, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.BreakIteratorResources, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.CollationData, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.FormatData, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.FormatData, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.CalendarData, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.CurrencyNames, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.LocaleNames, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.resources.TimeZoneNames, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.BreakIteratorInfo, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.BreakIteratorResources, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.CollationData, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.FormatData, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.text.resources.FormatData, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.logging.resources.logging, locale  with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.logging.resources.logging, locale ar with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.logging.resources.logging, locale en_US with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)
Adding bundle sun.util.logging.resources.logging, locale en with condition ConfigurationCondition(type=class java.lang.Object, runtimeChecked=true)

Using the latest version of GraalVM can resolve many issues.

• I tried with the latest version of GraalVM.

GraalVM Version

25

Operating System and Version

Windows 11

Troubleshooting Confirmation

• I tried the suggestions in the troubleshooting guide.

Run Command

.

Expected Behavior

.

Actual Behavior

.

Steps to Reproduce

Reproducer: https://github.com/Eng-Fouad/graal-native-date-locale

Additional Context

No response

Run-Time Log Output and Error Messages

No response

[zakkak]

Hi @Eng-Fouad as the reproducer is using Quarkus I tagged the issue accordingly and am going to answer based on that.

In Quarkus supported locales need to be defined through https://quarkus.io/guides/all-config#quarkus-core_quarkus-locales

Building with ./gradlew clean quarkusBuild -Dquarkus.locales=en,ar results in the following output for native and JVM runs respectively:

❯ ./build/graal-native-date-locale-1.0.0-runner 
__  ____  __  _____   ___  __ ____  ______ 
 --/ __ \/ / / / _ | / _ \/ //_/ / / / __/ 
 -/ /_/ / /_/ / __ |/ , _/ ,< / /_/ /\ \   
--\___\_\____/_/ |_/_/|_/_/|_|\____/___/   
2025-10-20 10:32:21,286 INFO  [io.quarkus] (main) graal-native-date-locale 1.0.0 native (powered by Quarkus 3.28.3) started in 0.004s. 
2025-10-20 10:32:21,286 INFO  [io.quarkus] (main) Profile prod activated. 
2025-10-20 10:32:21,286 INFO  [io.quarkus] (main) Installed features: [cdi, picocli]
2025-10-20 10:32:21,288 INFO  [io.fou.qua.i18.dem.LocalizedDateDemoCli] (main) arabicGregorianDate = الاثنين ٢٠\١٠\٢٠٢٥ م
2025-10-20 10:32:21,288 INFO  [io.fou.qua.i18.dem.LocalizedDateDemoCli] (main) englishGregorianDate = Monday 20/10/2025 AD
2025-10-20 10:32:21,288 INFO  [io.quarkus] (main) graal-native-date-locale stopped in 0.000s

❯ java -jar ./build/graal-native-date-locale-1.0.0-native-image-source-jar/graal-native-date-locale-1.0.0-runner.jar
__  ____  __  _____   ___  __ ____  ______ 
 --/ __ \/ / / / _ | / _ \/ //_/ / / / __/ 
 -/ /_/ / /_/ / __ |/ , _/ ,< / /_/ /\ \   
--\___\_\____/_/ |_/_/|_/_/|_|\____/___/   
2025-10-20 10:32:25,923 INFO  [io.quarkus] (main) graal-native-date-locale 1.0.0 on JVM (powered by Quarkus 3.28.3) started in 0.159s. 
2025-10-20 10:32:25,927 INFO  [io.quarkus] (main) Profile prod activated. 
2025-10-20 10:32:25,928 INFO  [io.quarkus] (main) Installed features: [cdi, picocli]
2025-10-20 10:32:25,972 INFO  [io.fou.qua.i18.dem.LocalizedDateDemoCli] (main) arabicGregorianDate = الاثنين ٢٠\١٠\٢٠٢٥ م
2025-10-20 10:32:25,973 INFO  [io.fou.qua.i18.dem.LocalizedDateDemoCli] (main) englishGregorianDate = Monday 20/10/2025 AD
2025-10-20 10:32:25,979 INFO  [io.quarkus] (main) graal-native-date-locale stopped in 0.006s

Note that I am not able to get in JVM mode arabicGregorianDate = السبت 18\10\2025 م using the reproducer.