Warning: unrecognized cop Rails/

Just in case you happened to copy the .rubocop.yml file from a different project like I did, in my case I just forgot to add the rubocop-rails gem, which includes the Rails/ cops.

Install it like any other gem and and require it in your .rubocop.yml file:

# Gemfile

gem 'rubocop', require: false
gem 'rubocop-rails', require: false

$ bundle install

# .rubocop.yml

require: rubocop-rails

$ rubocop

It seems like rubocop warnings is preventing rubocop to finish. In your version of rubocop there should be a setting called suppressRubocopWarnings try checking that if you know that the warnings doesn't need to be handled.

You can do that by typing cmd+shift+p and type Open User Settings. There you can search for rubocop and check the suppressRubocopWarnings checkbox, restart VSCode and it should work.

If you are using an older version of VSCode without the fancy UI, you should be able to add "ruby.rubocop.suppressRubocopWarnings": true, in your user settings json.

It seems to be common to get these kind of warnings if you share a rubocop.yml file across multiple projects.

Source: https://github.com/misogi/vscode-ruby-rubocop/pull/97