Default Ruby version for new apps is now 3.3.8

Change effective on 19 May 2025

The default Ruby version for new Ruby applications is 3.3.8. You’ll only get the default if the application does not specify a Ruby version.

Heroku highly recommends specifying your desired Ruby version. You can specify a Ruby version in your Gemfile:

ruby "3.3.8"

Once you have a Ruby version specified in your Gemfile, update the Gemfile.lock by running the following command:

$ bundle update --ruby

Make sure you commit the results to git before attempting to deploy again:

$ git add Gemfile Gemfile.lock
$ git commit -m "update ruby version"