Unable to register extension "sandbox" as extensions have already been initialized

Question

I have a problem installing Sonata project demo. After following this...

I get the following problem:

Unable to register extension "sandbox" as extensions have already been initialized.

  in /var/www/nfq/sandbox/sonata-sandbox/vendor/twig/twig/lib/Twig/Environment.php line 627
at Twig_Environment->addExtension(object(Twig_Extension_Sandbox))
  in /var/www/nfq/sandbox/sonata-sandbox/app/cache/dev/appDevDebugProjectContainer.php line 7111
at appDevDebugProjectContainer->getSonata_Formatter_Twig_Env_MarkdownService()
  in /var/www/nfq/sandbox/sonata-sandbox/app/bootstrap.php.cache line 211

Answer 1

The problem is in Sonata Formatter, I've the same problem, so I just commented the line who imports its configurations from config.yml

imports:
- { resource: parameters.yml }
- { resource: security.yml }
- { resource: fos_user.yml }

# Sonata Bundles
- { resource: sonata/sonata_admin.yml }
- { resource: sonata/sonata_block.yml }
- { resource: sonata/sonata_media.yml }
#- { resource: sonata/sonata_formatter.yml }
- { resource: sonata/sonata_news.yml }
- { resource: sonata/sonata_cache.yml }
- { resource: sonata/sonata_seo.yml }
- { resource: sonata/sonata_notification.yml }
- { resource: sonata/sonata_user.yml }

Edit:

Put this in required libraries in composer.json:

"twig/twig": "1.11.1"