How to fix Error starting daemon: error initializing graphdriver: kernel does not support overlay fs in Docker

First, verify your Linux kernel version meets the minimum requirements:

uname -r

Requirements:
- overlay driver: Linux kernel 3.18 or higher
- overlay2 driver (recommended): Linux kernel 4.0 or higher
- RHEL/CentOS exception: kernel 3.10.0-514 or higher

If your kernel is too old, you'll need to upgrade it or use a different storage driver.

Check if the overlay module is loaded and try loading it:

# Check if overlay module is loaded
lsmod | grep overlay

# Load the overlay module
sudo modprobe overlay

# Verify it loaded successfully
lsmod | grep overlay

If the module fails to load, your kernel may not have OverlayFS support compiled in. Check kernel configuration:

# Check kernel config for overlay support
grep -i overlay /boot/config-$(uname -r) 2>/dev/null || \
  zcat /proc/config.gz 2>/dev/null | grep -i OVERLAY

Look for CONFIG_OVERLAY_FS=y or CONFIG_OVERLAY_FS=m.

OverlayFS requires a compatible backing filesystem. Check what filesystem /var/lib/docker uses:

df -T /var/lib/docker

For XFS filesystems, verify d_type support is enabled:

xfs_info /var/lib/docker | grep ftype

You need ftype=1 for OverlayFS support. If it shows ftype=0, the XFS partition was formatted without d_type support.

For ext4 filesystems, d_type is supported by default since kernel 3.14.

Unsupported filesystems:
- NFS (doesn't support extended attributes)
- Some older ext3 configurations

Warning: This will destroy all data on the filesystem. Back up your data first!

If your XFS filesystem lacks d_type support (ftype=0), you need to reformat it:

# Stop Docker
sudo systemctl stop docker

# Back up Docker data if needed
sudo tar -cvzf docker-backup.tar.gz /var/lib/docker

# Unmount the filesystem (adjust device as needed)
sudo umount /var/lib/docker

# Reformat with ftype=1 for d_type support
sudo mkfs.xfs -n ftype=1 -f /dev/sdX

# Remount and restore
sudo mount /dev/sdX /var/lib/docker

# Start Docker
sudo systemctl start docker

If you cannot upgrade your kernel or fix the filesystem, configure Docker to use a different storage driver:

sudo mkdir -p /etc/docker
sudo tee /etc/docker/daemon.json <<EOF
{
  "storage-driver": "vfs"
}
EOF

sudo systemctl restart docker

Available alternatives:
- vfs: Universal fallback, works everywhere but very slow and uses more disk space
- devicemapper: Works on older systems (deprecated, not recommended for new deployments)
- btrfs: If your filesystem is Btrfs
- zfs: If your filesystem is ZFS

Note: The vfs driver doesn't use copy-on-write, so each layer is fully copied. Use it only as a last resort.

If your kernel is too old, consider upgrading:

Ubuntu/Debian:

sudo apt update
sudo apt install linux-generic
sudo reboot

RHEL/CentOS 7:

sudo yum update kernel
sudo reboot

RHEL/CentOS 8+ / Fedora:

sudo dnf update kernel
sudo reboot

After reboot, verify the new kernel and retry Docker:

uname -r
sudo modprobe overlay
sudo systemctl start docker

To make the overlay module load automatically at boot:

# Add overlay to modules to load at boot
echo "overlay" | sudo tee /etc/modules-load.d/overlay.conf

# Verify it's configured
cat /etc/modules-load.d/overlay.conf

Alternatively, on systemd-based systems:

sudo tee /etc/modules-load.d/containerd.conf <<EOF
overlay
br_netfilter
EOF

sudo modprobe overlay
sudo modprobe br_netfilter

After applying fixes, verify Docker is functioning correctly:

# Check Docker daemon status
sudo systemctl status docker

# Verify the storage driver in use
docker info | grep "Storage Driver"

# Run a test container
docker run --rm hello-world

The storage driver should now show "overlay2" (or your configured driver), and the test container should run successfully.