Symfony2.3 - Web Profiler not displayed on error - debugging

Question

I have a problem while working in the dev environnement of my Symfony 2.3 project.
The profiler works great in the debug toolbar, but when I have an error with my code, I dont get the usual Symfony profiler message but only the browser 500 message ("Server Error" on Chrome and a blank page on Firefox)
I have to read the apache error.log file to get the error message everytime I want to know what happened.
Here is the content of my config_dev.yml file :
imports:
- { resource: config.yml }
framework:
router: { resource: "%kernel.root_dir%/config/routing_dev.yml" }
profiler: { only_exceptions: false }
web_profiler:
toolbar: true
intercept_redirects: false
monolog:
handlers:
main:
type: stream
path: %kernel.logs_dir%/%kernel.environment%.log
level: debug
firephp:
type: firephp
level: info
chromephp:
type: chromephp
level: info
assetic:
use_controller: true
And my app_dev.php file :
<?php
use Symfony\Component\HttpFoundation\Request;
if (isset($_SERVER['HTTP_CLIENT_IP'])
|| isset($_SERVER['HTTP_X_FORWARDED_FOR'])
|| !in_array(#$_SERVER['REMOTE_ADDR'], array('127.0.0.1', 'fe80::1', '::1'))
) {
header('HTTP/1.0 403 Forbidden');
exit('You are not allowed to access this file. Check '.basename(__FILE__).' for more information.');
}
$loader = require_once __DIR__.'/../app/bootstrap.php.cache';
require_once __DIR__.'/../app/AppKernel.php';
$kernel = new AppKernel('dev', true);
$kernel->loadClassCache();
Request::enableHttpMethodParameterOverride();
$request = Request::createFromGlobals();
$response = $kernel->handle($request);
$response->send();
$kernel->terminate($request, $response);
Where should I start looking ?

Answer 1

I found answer!
in symfony 2.3:
The debugging tools are not enabled by default anymore and should be added to the web/app_dev.php
detailed here https://github.com/symfony/symfony-standard/blob/2.3/UPGRADE-2.3.md