The most common cause of this problem is that the Docker service isn’t running on your system. Other possible reasons include not having the necessary permissions to access the Docker socket, issues with how Docker is installed, or problems with the docker.sock file itself.
Now that you have an idea of the possible causes, let’s go through some practical solutions.
1. Start the Docker Service with systemctl
The first thing to check is whether Docker is running. The systemctl utility lets you start and manage system services. If Docker isn’t active, the Docker client won’t be able to communicate with the main Docker process, which causes this error. Running the systemctl start docker command starts the Docker service and should fix the problem if it was simply inactive.
2. Clean Up a ‘Failed Docker Pull’ and Start Docker Service
Sometimes, if a Docker pull fails, it can leave behind incomplete files that prevent the Docker daemon from starting correctly. Removing these leftover files gives Docker a fresh start. Restarting the Docker service afterwards helps clear up any issues that stuck or broken files can cause.
3. Start Dockerd (Docker Daemon) Service Directly
Dockerd is the main program (daemon) that runs in the background and handles all Docker tasks. In some cases, starting Dockerd directly can help, especially if using the systemctl command does not work for your system.
4. Start Docker with the Service Command
Manually starting Docker can make sure the service is running. You can use the sudo service docker start command to start Docker, which is useful if Docker didn’t start automatically after a system reboot.
5. Start the Docker Service with Snap
If you installed Docker using Snap, you need to make sure the Snap-managed Docker service is running. Snap sometimes requires you to start or connect services yourself. Use sudo snap start docker to make sure the Docker daemon is running as intended.
6. Start Docker for Users without Root Privileges
This error can also occur if you don’t have enough permission to access ‘unix:///var/run/docker.sock’. You can temporarily work around this by exporting the Docker host variable to use the local network interface via port 2375.
7. Reinstall Docker
Sometimes, issues with how Docker was installed—like corrupted files or wrong settings—might keep the Docker daemon from running correctly. Reinstalling Docker puts everything back into its default state and can fix problems caused by broken or conflicting setups.
