LoadError: Could not load the 'listen' gem (Rails 5)

If you are on rails 5 and you are using the default config/environments/development.rb file it will have this line of code in there.

config.file_watcher = ActiveSupport::EventedFileUpdateChecker

This requires the gem listen. This threw me for a bit as I was doing a rails 4 upgrades to a rails 5

edit: Forgot to mention that if you comment that line of code out it will not need the listen gem anymore.

You might by mistake have set bundle install --without at some point, I sure did anyways.

To revert this run:

bundle config --delete without

I also ran bundle config --delete with as I manually set with option as well by mistake. Running both should get you back to default behaviour.

After having deleted the without config I could successfully run a bundle install again and afterwards my rails s, rails db:migrate etc. worked.

You can confirm if this is your issue by running bundle install and look at the second last line in the output. If it states:

Gems in the groups development and test were not installed.

It's for sure above solution should work for you.

I used this: bundle install --without development

Error:

Could not load the 'listen' gem. Add gem 'listen' to the development group of your Gemfile (LoadError)

After this, use that code:

bundle config --delete without
bundle config --delete with

Finally

bundle install

I'm posting this as an answer, but I don't like it.

I can "fix" the problem by putting gem 'listen', '~> 3.1.5' in the global Gemfile (and removing it from :development). Then all the errors go away and everything works, but that seems wrong.

I'm having the same problem by running rails c.

By reading this other Stack Overflow post I did realize that it is normal that both bundle exec rake command or rails console are running in a default production environment.

I figured I will solve the issue either by:

1. adding export RAILS_ENV=production in ~/.bash_profile
2. explicitly writing the environment in which I want the command to execute like bundle exec rake a_rake:task RAILS_ENV=production rails console --env=production etc...