What Happened

CasaOS App Management talks to Docker through its API.
Docker recently updated from API 1.43 → 1.44.
Older CasaOS builds still spoke 1.43, and Docker now rejects clients using anything older.
Result: CasaOS can’t list containers, the apps API breaks with 500 errors, and the web UI greys everything out.

How to Confirm

Verify the missing API response:

curl -sS http://127.0.0.1/v2/app_management/web/appgrid

If that returns {"message":"Not Found"} or 500 Internal Server Error, the problem is confirmed.

Look for CasaOS errors:

journalctl -u casaos-app-management -n 100 --no-pager | grep 'client version'

You’ll see something like
client version 1.43 is too old. Minimum supported API version is 1.44.

Check Docker logs – it’s usually fine:

sudo systemctl status docker

The Fix

Tell CasaOS App Management to use Docker API 1.44:

sudo mkdir -p /etc/systemd/system/casaos-app-management.service.d
sudo tee /etc/systemd/system/casaos-app-management.service.d/override.conf >/dev/null <<'EOF'
[Service]
Environment=DOCKER_API_VERSION=1.44
EOF
sudo systemctl daemon-reload
sudo systemctl restart casaos-app-management

Then test again:

curl -sS http://127.0.0.1/v2/app_management/web/appgrid | head

You should now see JSON data listing your apps instead of an error, and the CasaOS UI will refresh with coloured, active tiles.

Why This Works

Systemd override files persist across reboots and updates.
By setting DOCKER_API_VERSION=1.44, CasaOS now speaks the same protocol version Docker expects.
The change is permanent until either Docker raises its API again or CasaOS updates its own code.