For those having trouble with mysql starting the cqrlog databases on Ubuntu:

The issue is the apparmor profile that ships with recent versions of Ubuntu is particularly restrictive. Check /var/log/syslog for the following:

Mar 16 11:01:12 ganymede kernel: [17286.306501] audit: type=1400 audit(1552748472.021:1159): apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/home/mike/.config/cqrlog/database/" pid=19929 comm="mysqld" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000

This can be fixed by adding the lines to /etc/apparmor.d/usr.sbin.mysqld

/home/mike/.config/cqrlog/** rwk, #modify for your correct path

then execute:
#systemctl force-reload apparmor.service

Ideally, the cqrlog install package would add an apparmor profile override for this.

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K5ROE