Daemon error that appears without changes in the system and with fresh installation.

[TheTechOddBug]

Docker was working in my Ubuntu 22.04 system till the day before yesterday but now I'm getting:
docker ps
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

Removing any docker piece and reinstalling following the install instructions in:

https://docs.docker.com/engine/install/ubuntu/#install-using-the-repository

I've ended with the same error.

My version is:
docker --version
Docker version 27.4.1, build b9d17ea

What has changed?

[thaJeztah]

Hard to tell without more details; I would recommend looking for daemon logs, for the docker service (which may be in your system logs) to see if an error is reported that caused the docker service not to start.

e.g., to get the last 100 log-entries from the docker service;

journalctl -n500 -u docker.service

But logs may also be in your syslog in other places, which can sometimes correlate daemon logs with other events happening on your system;

tail -n 500 /var/log/syslog

[thaJeztah]

But it's even possible there was no error, but the service was not configured to start automatically, so you could try starting it (systemctl start docker.service)