问题 I did a bundle update for my Jekyll site, then tried to run bundle exec jekyll serve . I got the following console message: Liquid Exception: Liquid syntax error (line 8): Unknown tag 'when' in vendor/bundle/ruby/2.4.0/gems/liquid-4.0.0/lib/liquid/locales/en.yml I've tried the following: uninstall/reinstall Jekyll uninstall/reinstall Gems uninstall/reinstall Ruby install RVM do rm Gemfile.lock run bundle update Curiously, when I run rvm list , it says * ruby-2.4.1 [ x86_64 ] . Even though the