Keep getting "PHP Warning: Error while sending QUERY packet"

Hello

I but keep getting " Cannot modify header information - headers already sent in functions.php" or "PHP Warning: Error while sending QUERY packet"

I changed the srver.cnf this way:
[mysqld]
max_allowed_packet = 1024M

and even reupload the functions.php file of the wordpress but no result.

How can solve it?

Thanks