AI Diagnostic Summary

docker: Cannot connect to Docker daemon

Well-Documented Error

This error matches known, documented patterns with reliable solutions.

Quick Fix (Most Common Solution)

Start Docker service or Docker Desktop
Add user to docker group

Seeing "docker: Cannot connect to Docker daemon"? This error can be frustrating, but it's usually fixable. It typically affects your development workflow or system. Below you'll find clear, step-by-step solutions to resolve this issue.

High confidence

What This Error Means

The Docker background service is not running or accessible.

Frequently documented in developer and vendor support forums.

Based on documented solutions and common real-world fixes.
Not affiliated with browser, OS, or device manufacturers.

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Common Causes

Docker service not started
User not in docker group
Docker Desktop not running

How to Fix

Start Docker service or Docker Desktop
Add user to docker group
Check Docker socket permissions

Last reviewed: April 2026 How we review solutions

Version note: On Linux, Docker Engine 24+ requires cgroup v2 by default. Older kernels (RHEL 7, CentOS 7) may need cgroup v1 compatibility mode.

Environment-Specific Commands

Linux (systemd)

sudo systemctl start docker
sudo systemctl enable docker # auto-start on boot
sudo usermod -aG docker $USER && newgrp docker

macOS

Open Docker Desktop from Applications
Or: open -a Docker
Wait for the whale icon in the menu bar to stop animating

Windows

Start Docker Desktop from Start Menu
If WSL2 backend: ensure WSL is updated (wsl --update)
Restart WSL if needed: wsl --shutdown then reopen terminal

Quick Diagnostic Path

If sudo docker works but docker without sudo does not → Your user is not in the docker group. Run: sudo usermod -aG docker $USER and log out/in.
If systemctl status docker shows "failed" → Check logs: journalctl -u docker.service -n 50 for the root cause.
If Docker Desktop is running but CLI still fails → Check the Docker context: docker context ls — ensure "desktop-linux" is selected.

If This Still Fails, Check

Rootless Docker installations use a different socket path (~/.docker/run/docker.sock) — set DOCKER_HOST accordingly
Snap-installed Docker on Ubuntu has a different service name: snap.docker.dockerd
Corporate VPN or firewall software may block the Docker socket — try disconnecting VPN to test

Full diagnostic sequence for Docker daemon issues

# Check daemon status
sudo systemctl status docker

# If inactive, start it
sudo systemctl start docker

# Verify socket exists
ls -la /var/run/docker.sock
# srw-rw---- 1 root docker 0 ... /var/run/docker.sock

# Test connection
docker info

OS-Specific Behavior

Docker Desktop vs Colima on macOS: Socket Path Conflicts

Docker daemon not running on macOS has two distinct root causes depending on your Docker installation. Docker Desktop for Mac installs a service that auto-starts at login and provides the Docker socket at /var/run/docker.sock. Colima — a popular lightweight alternative, especially on Apple Silicon — requires manual startup: colima start. If you recently switched from Docker Desktop to Colima or vice versa, the DOCKER_HOST environment variable may point to the wrong socket path. Docker Desktop uses unix:///var/run/docker.sock. Colima uses unix://~/.colima/default/docker.sock. If both were installed and one is running while the other is not, Docker CLI commands try to connect to the wrong socket and report "daemon not running" even though a daemon is actually running. Run docker context ls to see all configured Docker contexts and which is active. docker context use desktop-linux switches to Docker Desktop's context; docker context use colima switches to Colima. Setting DOCKER_CONTEXT=colima in your shell profile ensures the correct daemon is always targeted. On Linux, sudo systemctl status docker shows the daemon status. If it is failed or inactive, sudo systemctl start docker restarts it. Adding your user to the docker group (sudo usermod -aG docker $USER) followed by logging out and back in eliminates the need for sudo on all subsequent Docker commands.

Optional follow-up

Some users ask whether saving fixes for recurring errors would be useful when the same issue appears again.

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Explanations are based on documented fixes, real-world reports, and common system behavior. GetErrorHelp is independent and not affiliated with software vendors, device manufacturers, or service providers.

Frequently Asked Questions

How do I start Docker?

Run sudo systemctl start docker or start Docker Desktop.

How do I add user to docker group?

Run sudo usermod -aG docker $USER then log out and back in.

Related Resources

Also Known As

Docker container error
Docker build failure
Container runtime error
Docker daemon error

Common Search Variations

"docker container won't start"
"docker build error fix"
"docker image not found"
"container exited with error"
"docker daemon not responding"
"fix docker network error"

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Solutions are based on commonly documented fixes and may not apply in all situations.