InvalidArgumentException web_profiler Symphony

Bonjour,
Je débute avec Sympfony. J'ai actuellement un problème, peut importe la page que je charge, j'obtient cette erreur :

InvalidArgumentException in YamlFileLoader.php line 333:
There is no extension able to load the configuration for "web_profiler" (in /Users/******/Documents/dev_php/my_project/app/config/config_dev.yml). Looked for namespace "web_profiler", found "framework", "security", "twig", "monolog", "swiftmailer", "assetic", "doctrine", "sensio_framework_extra", "oc_platform", "debug", "sensio_distribution"

J'en ai déduit que le problème venait du web_profiler, mas je ne trouve pas.
Je suis le cour d'OpenClassroms http://openclassrooms.com/courses/developpez-votre-site-web-avec-le-framework-symfony2
Mon erreur a débuté lorsque j'ai fait le nettoyage au Chapitre 2 partie 2. Tous marchais parfaitement avant.


Voici la suite de mon erreur :

in YamlFileLoader.php line 333

at YamlFileLoader->validate(array('imports' => array(array('resource' => 'config.yml')), 'framework' => array('router' => array('resource' => '%kernel.root_dir%/config/routing_dev.yml', 'strict_requirements' => true), 'profiler' => array('only_exceptions' => false)), 'web_profiler' => array('toolbar' => true, 'intercept_redirects' => false), 'monolog' => array('handlers' => array('main' => array('type' => 'stream', 'path' => '%kernel.logs_dir%/%kernel.environment%.log', 'level' => 'debug'), 'console' => array('type' => 'console', 'bubble' => false, 'verbosity_levels' => array('VERBOSITY_VERBOSE' => 'INFO', 'VERBOSITY_VERY_VERBOSE' => 'DEBUG'), 'channels' => array('!doctrine')), 'console_very_verbose' => array('type' => 'console', 'bubble' => false, 'verbosity_levels' => array('VERBOSITY_VERBOSE' => 'NOTICE', 'VERBOSITY_VERY_VERBOSE' => 'NOTICE', 'VERBOSITY_DEBUG' => 'DEBUG'), 'channels' => array('doctrine')))), 'assetic' => array('use_controller' => true)), '/Users/hugofouquet/Documents/dev_php/my_project/app/config/config_dev.yml') in YamlFileLoader.php line 303

at YamlFileLoader->loadFile('/Users/hugofouquet/Documents/dev_php/my_project/app/config/config_dev.yml') in YamlFileLoader.php line 42

at YamlFileLoader->load('/Users/hugofouquet/Documents/dev_php/my_project/app/config/config_dev.yml', null) in DelegatingLoader.php line 45

at DelegatingLoader->load('/Users/hugofouquet/Documents/dev_php/my_project/app/config/config_dev.yml') in AppKernel.php line 33

at AppKernel->registerContainerConfiguration(object(DelegatingLoader)) in bootstrap.php.cache line 2616

at Kernel->buildContainer() in bootstrap.php.cache line 2568
at Kernel->initializeContainer() in bootstrap.php.cache line 2348
at Kernel->boot() in bootstrap.php.cache line 2379
at Kernel->handle(object(Request)) in app_dev.php line 28



Merci