How to render the same 404 page for all unknown requests, including images, in Rails 3.2 without specifying each file format individually?

Question

We use the following catch-all route in routes.rb for 404s:

# Catches all 404 errors and redirects
match '*url' => 'default#error_404'

But this generates a 500 internal server error below because we don't specifically catch PNG formats in error_404.

Started GET "/images/doesnotexistyo.png" for 71.198.44.101 at 2013-03-08 07:59:24 +0300
Processing by DefaultController#error_404 as PNG
  Parameters: {"url"=>"images/doesnotexistyo"}
Completed 500 Internal Server Error in 1ms

ActionView::MissingTemplate (Missing template default/error_404, application/error_404 with {:locale=>[:en], :formats=>[:png], :handlers=>[:erb, :builder]}. Searched in:
  * "/home/prod/Prod/app/views"

Ideally, all unknown requests would render the default#error_404 HTML action. We can't figure out how to get format.any to render the 404 HTML action. How can all unknown requests get rendered with the error 404 HTML response?

Answer 1

in Application Controller: Use rescue_from

rescue_from "ActionController::UnknownAction", :with => :render_404
rescue_from "ActionController::RoutingError",  :with => :render_404

def render_404
  respond_to do |format|
    format.html { render :template => "<PATH_OF_404_ERROR_TEMPLATE>", :status => 404 }       
    format.xml { head 404 }
    format.js { head 404 }
    format.json { head 404 }
  end
  return false
end