При попытке запустить joomla 1.5 на MySQL выше 5.6 вы получите ошибку:

Database Error: Unable to connect to the database:Could not connect to MySQLDatabase Error: Unable to connect to the database:Could not connect to MySQL

Решение:
в my.cnf добавить:

[mysqld]
character-set-server=utf8
collation-server=utf8_general_ci
init-connect="SET NAMES utf8"
skip-character-set-client-handshake
[mysqldump]
default-character-set=utf8

[client]
default-character-set=utf8

[mysql]
default-character-set=utf8