Error establishing a database connection (configuration)

Are you creating WordPress from scratch? You do not need to create the wp-config.php manually. Just open your installed WordPress from your browser and it will run an installer for you.

If you migrated from an existing WordPress installation (from another server/PC), check your database settings in wp-config.php file.

// ** MySQL settings ** //
/** The name of the database for WordPress */
define( 'DB_NAME', 'amadeus' );

/** MySQL database username */
define( 'DB_USER', 'root' );

/** MySQL database password */
define( 'DB_PASSWORD', '' );

/** MySQL hostname */
define( 'DB_HOST', 'localhost' );