MySql global variable disconnect_on_expired_password
This should give you a good idea as to which mysql user(s) is/are causing the error: 

SELECT user, host FROM mysql.user WHERE password_expired = 'Y';
To change disconnect_on_expired_password: Edit /etc/my.cnf, find the mysqld section, add this line:

disconnect_on_expired_password=OFF

Then restart mysqld.