base_controller.rb

module Admin
end
class Admin::BaseController < ApplicationController
#...
end

settings_controller.rb

class Admin::SettingsController < Admin::BaseController
  def redirect
    #...
    redirect_to :action => "index"    #<----here
    #...
  end
end

No key/value can be resolved for this "render" call
Also, no inspection reacts on unresolved values