How to fix it?
$ sudo gem install cocoapods Password: Fetching: i18n-0.7.0.gem (100%) Successfully installed i18n-0.7.0 Fetching: thread_safe-0.3.5.gem (100%) Successfully installed thread_safe-0.3.5 Fetching: tzinfo-1.2.2.gem (100%) Successfully installed tzinfo-1.2.2 Fetching: minitest-5.9.1.gem (100%) Successfully installed minitest-5.9.1 Fetching: concurrent-ruby-1.0.2.gem (100%) Successfully installed concurrent-ruby-1.0.2 Fetching: activesupport-5.0.0.1.gem (100%) ERROR: Error installing cocoapods: activesupport requires Ruby version >= 2.2.2. EDIT:
sudo gem install activesupport -v 4.2.6 sudo gem install cocoapods