In attempt to connect to the server under non-existing user, error below can be found in
CONFIG_TEXT: sshd: Unable to connect to Plesk Database: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (13)
SELinux is enabled on the server and set to
Plesk bug with ID PPPM-10120.
The error message can be safely ignored as it does not affect anything.
As a workaround to get rid of the error apply the steps below:
Log into the server via SSH.
Disable SELinux by executing the command below:
# setenforce 0