Rails & Devise: Failed registration attempt redirects to root url

You can override the Devise create action and redirect to your url:

# registrations_controller.rb
class RegistrationsController < Devise::RegistrationsController

  def create
    build_resource(sign_up_params)

    resource.save
    yield resource if block_given?
    if resource.persisted?
      if resource.active_for_authentication?
        set_flash_message! :notice, :signed_up
        sign_up(resource_name, resource)
        respond_with resource, location: after_sign_up_path_for(resource)
      else
        set_flash_message! :notice, :"signed_up_but_#{resource.inactive_message}"
        expire_data_after_sign_in!
        respond_with resource, location: after_inactive_sign_up_path_for(resource)
      end
   else
     clean_up_passwords resource
     set_minimum_password_length
     resource.errors.full_messages.each {|x| flash[x] = x}
     #redirect_to your_path
   end
  end

end 

And in routes:

resources :users
  devise_for :users, path: '', path_names: { sign_up: 'register', sign_in: 'login', sign_out: 'logout'}, :controllers => { :registrations => "registrations", :omniauth_callbacks => "callbacks" }