Symfony - Driver are mandatory if PDO instance

Question

I have a project in Symfony 2.1 I'm trying to run Composer install and it gives me this error:

The options 'driver' or 'driverClass' are mandatory if PDO instance is given to DriverManager :: getConnection ().

The system is:

Mac OS Sierra 10.12.6 (16G29)

PHP 7.0.22 (cli) (built: Sep 14 2017 09:01:19) (NTS)

Composer version 1.2.2

The Database configuration in Symfony in parameters.yml:

parameters:
     database_driver: pdo_mysql
     database_host: 127.0.0.1
     database_port: ~
     database_name: myDatabaseName
     database_user: myDatabaseUser
     database_password: myDatabasePassword

What is the problem?