Java 21 now available

Change effective on 20 September 2023

Heroku’s support for Java, Scala, Clojure, and Gradle now includes support for OpenJDK version 21. To use this version of the JDK, create a system.properties file in your application with the following contents:

java.runtime.version=21

After your next deployment, Heroku will install and run your app with OpenJDK 21. For more information, see the article on Heroku Support for Java in the Dev Center. For more information on JDK 21, see the official OpenJDK documentation.