OpenJDK 25 is now the default OpenJDK version for Java, Scala and Clojure apps

Change effective on 17 September 2025

We have changed the default OpenJDK version used by Java, Scala, and Clojure apps from 21 to 25.

This change only affects apps on the Heroku-24 stack that do not specify an OpenJDK version in their system.properties file. Apps with an explicit version configuration will continue to use their specified version.

See the OpenJDK 25 release notes to learn more about the new Java version.

We strongly recommend that you specify a OpenJDK version for your app in a system.properties file instead of relying on the buildpack’s default OpenJDK version.