Migrating to 8.16

This section discusses the changes that you need to be aware of when migrating your application to Elasticsearch 8.16.

See also What’s new in 8.17 and Release notes.

The following changes in Elasticsearch 8.16 might affect your applications and prevent them from operating normally. Before upgrading to 8.16, review these changes and take the described steps to mitigate the impact.

Elasticsearch 8.16 changes the version of the JDK that is included from version 22 to version 23. This changes the locale database that is used by Elasticsearch from the COMPAT database to the CLDR database. This can result in significant changes to custom textual date field formats, and calculations for custom week-date date fields.

For more information see custom date formats.

If you run Elasticsearch 8.16 on JDK version 22 or below, it will use the COMPAT locale database to match the behavior of 8.15. However, please note that starting with Elasticsearch 9.0, Elasticsearch will use the CLDR database regardless of JDK version it is run on.