Please update the following Timezone Updater sections under https://www.oracle.com/java/technologies/javase/tzupdater-readme.html Section- 1) Tool Updates - 2.3.0 Enhancements - JDK-8229818: Add workaround to TZUpdater for converting tzdata files from vanguard to rearguard (JDK 7u only) This bug needs to be made public. Summary: TZUpdater tool usage for JDK 7u only has a workaround that involves translating vanguard to rearguard format before computation of javazic data sources. A new TZUpdater property "tzupdater.forceUseOfVanguard" is introduced as a fallback option if the TZUpdater fails due to unforeseen circumstances. The new TZUpdater property can be enabled by setting "-Dtzupdater.forceUseOfVanguard=true". 2) Known Issues Please add: tzdata2020a The following issue is known to exist when processing tzdata2020a: Due to formatting changes in the IANA-maintained tzdata bundle, the TZUpdater tool fails to update to tzdata2020a for JDK 7u. The issue is being tracked under : https://bugs.openjdk.java.net/browse/JDK-8245950 Please follow the bug for a temporary workaround. tzdata2016g section can be removed as it is very old.