Problem happen when password of database in file config difference with current password of database horde.
Resolution: Change current password to same password in file config of horde.
/usr/local/cpanel/base/horde/config/conf.php
$conf['sql']['username'] = 'horde';
$conf['sql']['password'] = 'xxxxxxx';
mysql> UPDATE mysql.user SET Password=PASSWORD('YOUR-NEW-MYSQL-PASSWORD') WHERE User='horde';
mysql> FLUSH PRIVILEGES;
mysql> exitNguyễn Sĩ Nhàn