Comment 3 for bug 1574017

From log:

Setting up mysql-server-5.7 (5.7.11-0ubuntu6) ...
Installing new version of config file /etc/apparmor.d/usr.sbin.mysqld ...
Installing new version of config file /etc/init.d/mysql ...
Installing new version of config file /etc/init/mysql.conf ...
Installing new version of config file /etc/logrotate.d/mysql-server ...
Installing new version of config file /etc/mysql/debian-start ...
update-alternatives: using /etc/mysql/mysql.cnf to provide /etc/mysql/my.cnf (my.cnf) in auto mode
insserv: warning: script 'orientdb' missing LSB tags and overrides
insserv: script virtualbox: service vboxdrv already provided!
insserv: script virtualbox: service virtualbox already provided!
insserv: warning: script 'screen-cleanup' missing LSB tags and overrides
insserv: Default-Start undefined, assuming empty start runlevel(s) for script `screen-cleanup'
insserv: Default-Stop undefined, assuming empty stop runlevel(s) for script `screen-cleanup'
mysql_upgrade: Got error: 2002: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) while connecting to the MySQL server
Upgrade process encountered error and will not continue.
mysql_upgrade failed with exit status 11
dpkg: error processing package mysql-server-5.7 (--configure):
 subprocess installed post-installation script returned error exit status 1