big-bear-scripts/casaos-fix-docker-api-version

Fix Docker API Version Error for CasaOS

This script fixes common Docker errors with CasaOS including:

• Error response from daemon: client version 1.43 is too old. Minimum supported API version is 1.44
• OCI runtime create failed: runc create failed: unable to start container process: error during container init: open sysctl net.ipv4.ip_unprivileged_port_start file: reopen fd 8: permission denied
• Docker permission issues and corrupted overlay2 storage
• CVE-2025-52881 AppArmor issues in LXC/Proxmox environments

The Problem

These errors commonly occur with CasaOS when:

1. Docker gets upgraded to a very recent version (API 1.44+) that is incompatible with CasaOS's older Docker client
2. Docker overlay2 filesystem permissions become corrupted
3. Container runtime state becomes inconsistent
4. NEW: containerd.io 1.7.28-2 or newer causes AppArmor permission errors in LXC/Proxmox containers

CasaOS uses Docker API 1.43, and when the system Docker gets auto-upgraded or the storage becomes corrupted, it breaks compatibility.

Special Note for LXC/Proxmox Users

If you're running CasaOS or Docker in an LXC container (common with Proxmox), you may encounter the permission denied error after updating containerd. This is caused by CVE-2025-52881 security patches that conflict with AppArmor profiles in nested containers.

The error looks like:

failed to create shim task: OCI runtime create failed: runc create failed: 
unable to start container process: error during container init: 
open sysctl net.ipv4.ip_unprivileged_port_start file: reopen fd 8: permission denied

This script automatically detects LXC environments and installs containerd.io 1.7.28-1 (the last version before the breaking change) to prevent this issue.

References:

• GitHub Issue: https://github.com/opencontainers/runc/issues/4968
• Proxmox Forum: https://forum.proxmox.com/threads/docker-inside-lxc-net-ipv4-ip_unprivileged_port_start-error.175437/

What does this script do?

• Detects your operating system (Debian/Ubuntu-based)
• Detects LXC/Proxmox environment and adjusts containerd version accordingly
• Checks if CasaOS is installed
• Stops CasaOS services temporarily (if installed)
• Cleans Docker runtime state and fixes permissions
• Fixes overlay2 directory permissions
• Downgrades Docker to version 24.0.7 (compatible with both CasaOS and modern systems)
• Installs containerd.io 1.7.28-1 in LXC/Proxmox to avoid CVE-2025-52881 AppArmor issues
• Configures Docker daemon with proper settings
• Holds Docker packages to prevent automatic upgrades
• Removes standalone docker-compose if present
• Installs Docker Compose plugin
• Restarts Docker service properly
• Restarts CasaOS services (if installed)
• Intelligently detects and fixes the sysctl permission denied error

Run command

bash -c "$(wget -qLO - https://raw.githubusercontent.com/bigbeartechworld/big-bear-scripts/master/casaos-fix-docker-api-version/run.sh)"

Can't Resolve Domain

To resolve this issue, please follow these steps:

1. Copy the contents of run.sh from this repository.
2. Create a file named run.sh on your server.
3. Execute the following command on your server:

bash run.sh

What causes these errors?

These errors occur when:

• Docker gets auto-upgraded to version 25+ or 26+ (API 1.44+)
• CasaOS still uses Docker API 1.43 in older versions
• There's a version mismatch between CasaOS's Docker client and the system's Docker daemon
• System updates automatically upgrade Docker without considering CasaOS compatibility
• Docker overlay2 storage permissions become corrupted
• Container runtime (runc/containerd) state becomes inconsistent
• Improper system shutdowns or Docker crashes leave stale state files
• containerd.io 1.7.28-2 or newer in LXC/Proxmox (CVE-2025-52881 AppArmor conflict)

Requirements

• Debian or Ubuntu-based Linux distribution
• Sudo privileges or root access
• Active internet connection
• CasaOS installed (optional - script works without it too)

After running the script

You can verify the fix by running:

docker version

Both the client and server API versions should now be compatible. The script installs Docker 24.0.7 which:

• Supports API version 1.43 (compatible with older CasaOS)
• Is stable and well-tested
• Is held at this version to prevent auto-upgrades

Preventing future issues

The script automatically holds Docker packages to prevent automatic upgrades:

sudo apt-mark hold docker-ce docker-ce-cli containerd.io

Important for LXC/Proxmox users: The script holds containerd.io at version 1.7.28-1 to prevent the CVE-2025-52881 AppArmor issue. Do not upgrade containerd until this issue is resolved upstream.

If you want to allow Docker upgrades in the future (after confirming CasaOS compatibility), run:

sudo apt-mark unhold docker-ce docker-ce-cli containerd.io

⚠️ Warning for LXC users: Before unholdingcontainerd.io, check if the AppArmor issue has been fixed:

• Check: https://github.com/opencontainers/runc/issues/4968
• Or test in a non-production environment first

Version Information

• Docker CE: 24.0.7
• Docker API: 1.43 compatible
• containerd.io: 1.7.28-1 (for LXC/Proxmox environments)
• Works with CasaOS 0.4.x series

Alternative Solutions for LXC/Proxmox (Advanced)

If you prefer not to downgrade containerd, you can modify the LXC container configuration on the Proxmox host:

Option 1: Disable AppArmor for the container (in /etc/pve/lxc/$CTID.conf):

lxc.apparmor.profile: unconfined
lxc.mount.entry: /dev/null sys/module/apparmor/parameters/enabled none bind 0 0

Option 2: Wait for upstream fixes:

• Proxmox/LXC to update their AppArmor profiles
• containerd/runc to implement workarounds

This script uses the downgrade approach as it's the safest and most reliable solution that doesn't require host-level configuration changes.