Heroku-18 is now the default stack

Change effective on 13 September 2018

Recently the Heroku-18 stack became generally available. As of today, newly created apps will now use Heroku-18 by default.

Check out Dev Center to learn more about testing and upgrading your app to Heroku-18.

Known Issues

Ruby 2.3 or under does not work on Heroku-18. If you’re using Heroku CI with Ruby 2.3 or under you will need to manually specify to use a different stack in your app.json:

"stack": "heroku-16"