16.04 upgrade broke mysql-server - Ask Ubuntu

my overall upgrade went well, left critically lingering issue of mysql-server not being able install itself, , nothing trying gets work.

this error see when trying install/reinstall it:

setting mysql-server-5.7 (5.7.11-0ubuntu6) ... job mysql.service failed because control process exited error code. see "systemctl status mysql.service" , "journalctl -xe" details. invoke-rc.d: initscript mysql, action "start" failed. dpkg: error processing package mysql-server-5.7 (--configure):  subprocess installed post-installation script returned error exit status 1 dpkg: dependency problems prevent configuration of mysql-server:  mysql-server depends on mysql-server-5.7; however:   package mysql-server-5.7 not configured yet.  dpkg: error processing package mysql-server (--configure):  dependency problems - leaving unconfigured no apport report written because error message indicates followup error previous failure.                    processing triggers systemd (229-4ubuntu4) ... processing triggers ureadahead (0.100.0-19) ... errors encountered while processing:  mysql-server-5.7  mysql-server e: sub-process /usr/bin/dpkg returned error code (1) 

i've tried removing it, though doing attempts install mariadb because of dependencies (?). suggestions on can fix welcome.

edit: looks i'm not one: https://bugs.launchpad.net/ubuntu/+source/mysql-5.7/+bug/1573279

the instructions @andrew-beerman posted on right track, though aren't quite clear me , seem recommend more necessary. pieced answer above , helpful post in bug thread.

these steps took correct this:

1. back my.cnf file in /etc/mysql , remove or rename it

   sudo mv /etc/mysql/my.cnf /etc/mysql/my.cnf.bak 

2. remove folder /etc/mysql/mysql.conf.d/ using

   sudo rm -r /etc/mysql/mysql.conf.d/ 

3. verify don't have my.cnf file stashed somewhere else (i did in home dir!) or in /etc/alternatives/my.cnf use

   sudo find / -name my.cnf 

4. backup , remove /etc/mysql/debian.cnf files (not sure if needed, in case)

   sudo mv /etc/mysql/debian.cnf /etc/mysql/debian.cnf.bak sudo apt purge mysql-server mysql-server-5.7 mysql-server-core-5.7 sudo apt install mysql-server 

5. in case syslog shows error "mysqld: can't read dir of '/etc/mysql/conf.d/'" create symbolic link:

   sudo ln -s /etc/mysql/mysql.conf.d /etc/mysql/conf.d 

   then service should able start sudo service mysql start.

that got working!