the unit docker.socket has entered the code example

Example: the unit docker.socket has entered the

In the present case the same error occured after the latest manjaro update (2020-01-20).
Tried to change the systemd docker service, as adviced in other cases, but I reverted those changes and finally this was solved with:

a reboot of the system
(like advised here: https://www.reddit.com/r/archlinux/comments/7ya4ug/installing_docker_on_arch_linux/)