Migrate to new server and database

Hi
I need to move my multisite Wp to a subdomain and also change the databse server

I'm using Multi-DB with 256 Dbs

After the file movement and database dump and reloading

I change DB server IP, username and password on file:
db-config.php and wp-config

But I receive an error (my site is in spanish):
Error estableciendo una conexión con la base de datos

If I enable WP_DEBUG I see:
Notice: Undefined property: m_wpdb::$real_escape in /var/www/vhosts/beta.wasanga.com/html/wp-includes/wp-db.php on line 566 Notice: Undefined property: m_wpdb::$real_escape in

Could you help me to solve this problem?

Thank you in advanced

Carlos