Fix it by changing the password in /etc/mysql/debian.cnf
Or:
GRANT ALL PRIVILEGES ON *.* TO 'debian-sys-maint'@'localhost' IDENTIFIED BY 'password.in.debian.cnf.file';
If you have another root user for MySQL.
Update 5/2/2016: Nice one liner from Shahar Evron here:
http://arr.gr/blog/2014/06/fixing-logrotate-errors-and-other-mysql-issues-on-ubuntu-debian/
And in case the link or site goes away, here is the relevant bit:
echo "SET PASSWORD FOR 'debian-sys-maint'@'localhost' = PASSWORD('`sudo cat /etc/mysql/debian.cnf | grep password | head -n 1 |
awk -F= '{ gsub(/[ \t]+/, "", $2); print $2 }'`');" | mysql -u root -p