The dist file “app/config/parameters.yml.dist” does not exist. Check your dist-file config or create it.

Are you upgrading symfony to 2.3. Bum! This will be the problem you would face after upgrading the composer.json file and trying to do 

composer.phar install 

the solution is simple. Just copy the existing parameters.yml file from app/config/ folder to new file called parameters.yml.dist and rerun the command