The combination of Bundler 2, Heroku's Ruby buildpack, and Rails' own
binstubs for Rails 5.2 appears to cause a conflict when starting the
console for an application bundled with Bundler 2.x.
% production console
Running rails console on ⬢ app-production... up, run.5165 (Standard-1X)
You must use Bundler 2 or greater with this lockfile.
The solution is to invoke the console with bundle exec, which gets
around the mismatch of Bundler 1.x and 2.x and blocks the Rails console
from starting.
The combination of Bundler 2, Heroku's Ruby buildpack, and Rails' own binstubs for Rails 5.2 appears to cause a conflict when starting the console for an application bundled with Bundler 2.x.
The solution is to invoke the console with
bundle exec, which gets around the mismatch of Bundler 1.x and 2.x and blocks the Rails console from starting.