Whose Error Is It?
Docker printed this
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
What it meansThe Docker CLI could not reach the daemon through its Unix socket, so either the daemon is not running or you lack access to the socket.
The first thing to checkStart the daemon with sudo systemctl start docker or open Docker Desktop; if it is running, add your user to the docker group and log back in.