Docker daemon unavailable

April 30, 2026 · View on GitHub

Playbook ID: docker-daemon-unavailable Category: runtime Severity: high Tags: docker, daemon, socket, runtime, ci

What this failure means

Docker could not reach the daemon socket or service, so the step failed before it could inspect containers or run a build.

Common log signals

Cannot connect to the Docker daemon
Cannot connect to the docker daemon
Is the docker daemon running?
Docker daemon is not running
failed to connect to the Docker daemon
failed to connect to docker daemon
unable to connect to the Docker daemon
dockerd failed to start

Diagnosis

Docker could not reach the daemon socket or service, so the step failed before it could inspect containers or run a build.

This usually means the daemon is stopped, the socket path is wrong, or the environment does not expose Docker at all.

Fix steps

Check whether the Docker daemon is actually running on the host or runner.
Verify the expected socket is mounted or the Docker service is available to the job.
If you are using Docker-in-Docker, confirm the sidecar or service container started before the job step.
Re-run a minimal probe from the same environment:
```
docker info
docker ps
```

Validation

docker info succeeds from the same job environment.
Re-run the failing step and confirm the Docker daemon is reachable.

Likely files to inspect

Dockerfile
.github/workflows/*.yml
.github/workflows/*.yaml
.gitlab-ci.yml
docker-compose*.yml

Run Faultline

faultline analyze build.log
faultline explain docker-daemon-unavailable
faultline workflow build.log --json --mode agent

Search phrases this page answers

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Generated from playbooks/bundled/log/runtime/docker-daemon-unavailable.yaml. Do not edit directly — run make docs-generate.