Symfony fatal error when trying to run configurator

I successfully completed the configuration check on web/config.php when installing Symfony开发者_开发技巧 on a U10 LAMP server, but now running across this error when trying to run web/app_dev.php/_configurator/:

Fatal error: Interface 'Symfony\Bridge\Doctrine\RegistryInterface' not found in /var/www/symfony/vendor/symfony/src/Symfony/Bundle/DoctrineBundle/Registry.php on line 26

Did I forget to install something?

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You are missing Doctrine bridge for some reason. I guess something went wrong when you installed vendors (github might have been down for a minute and it just skipped this part).

Try to reinstall vendors:

./bin/vendors install

Or just download Symfony2 with pre-installed vendors.