How to fix Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: connect: no such file or directory in Docker

First, verify whether the Docker daemon is actually running:

On systems with systemd (most modern Linux):

sudo systemctl status docker

Look for "Active: active (running)". If it shows "inactive" or "failed", the daemon is not running.

Alternative check:

ps aux | grep dockerd

If you see a dockerd process, the daemon is running but might be using a different socket.

If Docker is not running, start the service:

Using systemctl (recommended):

sudo systemctl start docker

Using service command (older systems):

sudo service docker start

Verify it started:

sudo systemctl status docker

The socket file should now exist:

ls -la /var/run/docker.sock

To prevent this issue after reboots, enable the Docker service:

sudo systemctl enable docker

This creates the necessary symlinks for systemd to start Docker automatically.

Verify it's enabled:

sudo systemctl is-enabled docker

Should output "enabled".

Sometimes the Docker service gets "masked", preventing it from starting:

Check if masked:

sudo systemctl status docker

If you see "Loaded: masked", run:

sudo systemctl unmask docker.service
sudo systemctl unmask docker.socket
sudo systemctl start docker

This situation can occur after certain system updates or when Docker was previously disabled intentionally.

If you're using Docker Desktop on macOS or Windows:

macOS:
1. Open Finder and go to Applications
2. Double-click "Docker" to launch Docker Desktop
3. Wait for the whale icon in the menu bar to stop animating

Windows:
1. Click Start menu and search for "Docker Desktop"
2. Launch the application
3. Wait for the whale icon in the system tray to become stable

Enable default socket (Docker Desktop):
1. Open Docker Desktop Settings
2. Go to Advanced
3. Enable "Allow the default Docker socket to be used"
4. Click "Apply & Restart"

If using Docker Desktop with WSL on Windows, ensure integration is enabled:

1. Open Docker Desktop
2. Go to Settings > Resources > WSL Integration
3. Enable integration for your Linux distribution
4. Click "Apply & Restart"

Inside WSL, verify the socket:

ls -la /var/run/docker.sock

If the socket is still missing, restart WSL:

# In PowerShell (not WSL)
wsl --shutdown

Then reopen your WSL terminal and try again.

If Docker is configured to use a different socket, the default location won't have a socket:

echo $DOCKER_HOST

If this shows a value like tcp://localhost:2375 or a different socket path, either:

Option 1: Unset to use default socket:

unset DOCKER_HOST
docker info

Option 2: Point to the actual socket location:

# Find where Docker is listening
sudo find / -name "docker.sock" 2>/dev/null

Common alternative locations:
- /run/docker.sock
- ~/.docker/run/docker.sock
- /var/run/docker/docker.sock

If you have both Snap and apt versions of Docker installed, they can conflict:

Check for Snap Docker:

snap list | grep docker

Check for apt Docker:

dpkg -l | grep docker

If both are present, remove one:

Remove Snap Docker:

sudo snap remove docker

Or remove apt Docker:

sudo apt remove docker docker-engine docker.io containerd runc

Then restart your system and reinstall Docker using your preferred method.

If Docker is not properly installed, install it:

Ubuntu/Debian:

# Remove old versions
sudo apt remove docker docker-engine docker.io containerd runc

# Add Docker repository
sudo apt update
sudo apt install ca-certificates curl gnupg
sudo install -m 0755 -d /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
sudo chmod a+r /etc/apt/keyrings/docker.gpg

echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

# Install Docker
sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

# Start and enable
sudo systemctl start docker
sudo systemctl enable docker

After installation, log out and back in, or restart your system.