Are you using JQuery? In that case, you can try "rails g
jquery:install". I had the same problem a few days ago. It's an issue
related to DELETE actions.
For the sign_out url you should have DELETE method.
If you run 'rake routes' inside your project path, you could see this
route, and there is no GET /users/sign_out at all, only DELETE /users/
sign_out.
So you should use some mechanisme to make <%= link_to "Sign out",
destroy_user_session %> = <a href="/users/sign_out"
data_method="delete">Sign out</a>. One of the way is to use JQuery gem
and make sure you have all javascript enabled.