Plesk Update failed: There is a MySQL server running, but we failed in our attempts to stop it.

Symptoms

- Plesk Update failed with following error:

# cat /var/log/plesk/panel.log
[...]
Preparing to unpack .../mariadb-server-10.0_10.0.32-0+deb8u1_amd64.deb ...
47146
There is a MySQL server running, but we failed in our attempts to stop it.
Stop it yourself and try again!
dpkg: warning: subprocess old pre-removal script returned error exit status 1
dpkg: trying script from the new package instead ...
47146
There is a MySQL server running, but we failed in our attempts to stop it.
Stop it yourself and try again!
dpkg: error processing archive /var/cache/apt/archives/mariadb-server-10.0_10.0.32-0+deb8u1_amd64.deb (--unpack):
subprocess new pre-removal script returned error exit status 1
insserv: warning: script 'apf' missing LSB tags and overrides
Errors were encountered while processing:
/var/cache/apt/archives/mariadb-server-10.0_10.0.32-0+deb8u1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
[...]

- Same issue happens trying to install MariaDB-Server-10.0 from apt-get install CLI utility

Cause

MariaDB Server pre-removal script fails to stop current MySQL process. For more information about this issue, check Official Debian bug notes .

Resolution

1. Perform a full database backup:

# mysqldump -uadmin -p`cat /etc/psa/.psa.shadow` -f --all-databases > /root/all_databases_backup`date +%F-%s`.sql

2. Stop MySQL service manually:

# systemctl stop mysql.service

3. Check if mysql still is running:

# pidof -c /usr/sbin/mysqld
7327

# ps awufx | grep mysql
root 7519 0.0 0.0 12668 1560 pts/0 S+ 21:35 0:00 | \_ grep mysql
root 7187 0.0 0.0 21820 3504 ? S 21:32 0:00 /bin/bash /usr/bin/mysqld_safe
mysql 7327 0.1 2.0 624472 81944 ? Sl 21:32 0:00 \_ /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --skip-log-error --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/run/mysqld/mysqld.sock --port=3306
root 7328 0.0 0.0 23684 2476 ? S 21:32 0:00 \_ logger -t mysqld -p daemon.error

4. Kill mysql processes manually (PID's coming from the example, please set yours):

# kill -9 7187 7327 7328

5. Be sure that there aren't mysql processes running:

# pidof -c /usr/sbin/mysqld

6. Install/Update MariaDB-Server manually with apt-get install CLI utility:

# apt-get install mariadb-server-10.0
[...]
Preparing to unpack .../mariadb-server-10.0_10.0.32-0+deb8u1_amd64.deb ...
Unpacking mariadb-server-10.0 (10.0.32-0+deb8u1) over (10.0.30-0+deb8u2) ...
Processing triggers for systemd (215-17+deb8u7) ...
Processing triggers for man-db (2.7.0.2-5) ...
Setting up mariadb-server-10.0 (10.0.32-0+deb8u1) ...
insserv: warning: script 'apf' missing LSB tags and overrides