What does this docker log entry mean?

I had docker package installed through apt and snap at the same time. So the issue is fixed by removing docker through the snap packaging system.

# apt list --installed | grep docker   
docker/bionic,now 1.5-1build1 amd64 [installed]
docker-ce/bionic,now 5:19.03.5~3-0~ubuntu-bionic amd64 [installed]
docker-ce-cli/bionic,now 5:19.03.5~3-0~ubuntu-bionic amd64 [installed,automatic]

# snap list | grep docker
docker                18.09.9                     418   stable    canonical✓  -

# snap remove docker
docker removed

Someone at Cannonical screw things up few hours ago - it's tracked on launchpad - https://bugs.launchpad.net/ubuntu/+source/snapd/+bug/1852720

My system was installed yesterday with docker only and same as rest of folks here - syslog killed entire free space on disk, purging docker from snap helped.

You have multiple docker services running. Looks like dockerd is trying to access the different installation of containerd, spamming syslog.

In my case, the teamcity agent and docker installation was conflicted.

sudo apt-get purge docker-ce
sudo apt autoremove
sudo rm -rf /var/lib/docker
sudo truncate -s 0 /var/log/syslog

Ran those commands above and restarted. everything went okay.