Rails4: like order with sqlite3 is OK but PG not working

There is no problem with sqlite 3 but 'PG :: GroupingError: ERROR' appears in posgresql's environment.

I want to display posts with a lot of total by using paginate's gem in the order of total of like, but it is displayed without problem in sqlite 3

posts_controller.rb

  def popular
    @posts = Post.joins(:likes).group(:post_id).order("count(*) desc").paginate(:page => params[:page], :per_page => 18)
  end

However, in the postgres environment, 'PG :: GroupingError: ERROR: column' posts.id 'must appear in the GROUP BY clause or be used in an aggregate function' will be displayed and an error will be displayed.

It will be very helpful to tell me

thank you