Postfix: Can't create email accounts

Hi guys, i upgraded mysql to 5.7 and now i can't add email account to clients, when i try to add it's going to reload page and nothing! Can you please help me?

edit your /usr/my.cnf:

#nano /usr/my.cnf

add this line
sql_mode=NO_ENGINE_SUBSTITUTION

Ctrl-X , Y

Restart mysqld
# service mysqld restart