Warning during plesk Onyx Upgrade

Hi Everybody,

I have one issue, when I try upgrade the plesk 12.5 to Onyx I have the message bellow on /var/log/plesk/install/autoinstaller3.log:

Errors found: 0; Warnings found: 1

Error:
WARNING: [MYSQL ERROR] Unable to connect database. The reason of problem:

[2017-02-22 09:02:32.546755] Execute command /usr/local/psa/admin/bin/send-error-report install --version 17.0.17
[2017-02-22 09:02:32.547975] Warning: Failed to attach to cgroup /sys/fs/cgroup/systemd/user/root/tasks, installer...

Warning during plesk Onyx Upgrade