Symfony2 installation: symfony.webconfigurator service

I try to configure symfony2 on wamp, but I get a mistake:

Fatal error: Uncaught exception 'InvalidArgumentException' with message 'The service "symfony.webconfigurator" does not exist.' in F:\xamppx\xampp\htdocs\Symfony\app\bootstrap.php:112 Stack trace: 
#0 F:\xamppx\xampp\htdocs\Symfony\vendor\bundles\Symfony\Bundle\WebConfiguratorBundle\SymfonyWebConfiguratorBundle.php(28): Symfony\Component\DependencyInjection\Container->get('symfony.webconf...') 
#1 F:\xamppx\xampp\htdocs\Symfony\app\bootstrap.php(543): Symfony\Bundle\WebConfiguratorBundle\SymfonyWebConfiguratorBundle->boot() 
#2 F:\xamppx\xampp\htdocs\Symfony\app\bootstrap.php(559): Symfony\Component\HttpKernel\Kernel->boot() 
#3 F:\xamppx\xampp\htdocs\Symfony\web\app_dev.php(15): Symfony\Component\HttpKernel\Kernel-开发者_开发问答>handle(Object(Symfony\Component\HttpFoundation\Request)) 
#4 {main} thrown in F:\xamppx\xampp\htdocs\Symfony\app\bootstrap.php on line 112

Why?

you can also try this,

This is the official Symfony2 repository is hosted on Github

Link: https://github.com/symfony/symfony

Do you use Symfony Standard 2.0.0 PR7 .tgz ? Try Symfony Standard 2.0.0 PR7 .zip, i fixed this issue with.

i have this error to... You have to take .zip arvive of PR8 Take vendor, change config, appKeernel and autoload to finish, in comand line run the build/build_bootstrap.php