Prestashop The database selection cannot be made.

when migrating prestahsop from one web site to other 'The database selection cannot be made.' error happened... although my user had ALL PRIVILEGES 

privs ...
granting explicit privilerges to my user (select , insert, duplicate etc ...) solved the problem.

grant select on ON db_ps.* TO 'your_user'@'host';
grant insert on ON db_ps.* TO 'your_user'@'host';
grant delete on ON db_ps.* TO 'your_user'@host';
grant update on ON db_ps.* TO 'your_user'@'host';

or simply

grant SELECT,INSERT,UPDATE,DELETE ON `db_ps`.* TO 'your_user'@'host';

MySQL doc here