Cannot connect to the Docker daemon. Is 'docker -d' running on this host?

Question

I am trying to run my Docker commands, but I am facing the notification error in the title. I tried running:

ps auxww | grep docker

but sti

Answer 1

In my case I had multiple docker instances running so it didn't know what to attach to. After killing them and restarting, my problem was solved.

Answer 2

How about launching the daemon

sudo service docker start

should do the trick.

Or

sudo docker -d

Answer 3

If you can verify that the docker daemon is running then it may be that your user is not allowed to access docker.

To do this add yourself to the docker group.

sudo usermod -aG docker <userid>

Remember to do a re-login or otherwise apply/activate the new group permission.

newgrp docker