Capybara Cucumber timeout with Rails 5.0.1

Question

Using ActionCable on Rails 5.0.1 my previously working cucumber test is now giving:

Rack application timed out during boot (RuntimeError)

On visiting a page

My cucumber env file contains:

require 'cucumber/rails'
require 'capybara/poltergeist'
# Require to enable javascript in tests
# See https://github.com/teampoltergeist/poltergeist
Capybara.javascript_driver = :poltergeist
# Required to test action cable.
# See http://stackoverflow.com/questions/35897189/capybara-not-working-with-action-cable
Capybara.server = :puma

Answer 1

You probably updated puma to 3.7.0 - It has a serious bug that will be fixed in 3.7.1 when it's released. For now revert to 3.6.9

gem 'puma', '!= 3.7.0'