env['warden'] not working with Rails 5

I had the same problem, but it turned out my issue was because I had two Devise models: User and Customer, since User was used for admin stuff, Customer was set to Warden's default_scope. So to access the user scope, I had to do the following

env['warden'].user(:user)

The symbol at the end defines the scope to use.

Here's where I found information on Warden's Scoped Users: https://github.com/wardencommunity/warden/wiki/Scopes#scoped-user-access

I found solution on this article https://rubytutorial.io/actioncable-devise-authentication/

Im not sure how it works, but it does the deal. How it would help for people with similar problem.

module ApplicationCable
  class Connection < ActionCable::Connection::Base
    identified_by :current_user

    def connect
      self.current_user = find_verified_user
      logger.add_tags 'ActionCable', current_user.email
    end

    protected
    def find_verified_user
      verified_user = User.find_by(id: cookies.signed['user.id'])
      if verified_user && cookies.signed['user.expires_at'] > Time.now
        verified_user
      else
        reject_unauthorized_connection
      end
    end

  end
end

And I also created /config/initializers/warden_hooks.rb file

Warden::Manager.after_set_user do |user,auth,opts|
  scope = opts[:scope]
  auth.cookies.signed["#{scope}.id"] = user.id
  auth.cookies.signed["#{scope}.expires_at"] = 60.minutes.from_now
end

Warden::Manager.before_logout do |user, auth, opts|
  scope = opts[:scope]
  auth.cookies.signed["#{scope}.id"] = nil
  auth.cookies.signed["#{scope}.expires_at"] = nil
end