Handling routing error in Rails 4

application_controller.rb

def routing_error
  respond_to do |format|
    format.html { render :file => "#{Rails.root}/public/404", :layout => false, :status => :not_found }
    format.xml  { head :not_found }
    format.any  { head :not_found }
  end
end

routes.rb

match '*unmatched_route', :to => 'application#routing_error', via: [:get, :post]