Situation: After trying to use slick plugin of jquery using log-in user, I want to sign out. The screen shows 'No routes matches '/users/sign_out' ' when I click the link of sign-out. Before trying slick plugin, /users/sign_out route of devise gem works as normal.

Cause: The addtional js jquery-migrate-min, which required for slick plugin, makes rails misunderstood original route for /users/sign_out .

Environment: Rails 4.2.5.1, Devise 3.5.5, Jquery-migrate-rails 1.2.1

Solution: Remove statement: //= require jquery-migrate-min from app/assets/javascripts/application.js and restart your rails app.