Custom error500 / 400 page in symfony 1.4

Custom 400 page:

In config/settings.yml,
all:
  .actions:
    error_404_module:       error
    error_404_action:       404

Then when a page is not found, it will forward to "<your_domain>/error/404".

Custom 500 page:

1. Create "error" folder under "config"
2. create "error.html.php" under "config/error"