Bundler version 2.6.9 and 2.7.2 are now available for Ruby Applications
Change effective on 21 October 2025
The Ruby Buildpack installs a version of bundler based on the major and minor version listed in the Gemfile.lock under the BUNDLED WITH key:
BUNDLED WITH2.6.x will receive bundler2.6.9BUNDLED WITH2.7.x will receive bundler2.7.2
It is strongly recommended that you have both a RUBY VERSION and BUNDLED WITH version listed in your Gemfile.lock. If you do not have those values, you can generate them and commit them to git:
$ bundle update --ruby
$ git add Gemfile.lock
$ git commit -m "Update Gemfile.lock"
Applications without these values specified in the Gemfile.lock may break unexpectedly when the defaults change.