Comment 18 for bug 1571865

I found that when it tried to install mysql-5.7 - 5.7.13-0ubuntu0.16.04.2, dpkg just hung forever at postinst (in this case, forever means overnight). The only way around this was to kill -9 the two mysqld processes that ran (I think one was already running, and then another ran when I killed the first).

Then I upgraded to yakkety and it installed mysql-server-5.7_5.7.13-0ubuntu4_amd64.deb and I had exactly the same problem. Killing the mysqld processes as before allowed dpkg to continue.

I found some other issues too when I tried reinstalling from scratch - /etc/mysql/my.cnf has the line "!includedir /etc/mysql/conf.d/", but /etc/mysql/conf.d no longer exists if you have purged mysql before reinstalling, so the server won't start up and configuration therefore fails. I had to comment the line out manually to get it to work.