henrygd/beszel · error

docker version request failed: %s

Error message

docker version request failed: %s

What it means

checkDockerVersion pings the daemon's /version endpoint to decide feature availability. This error is returned when the version HTTP request completes but with a non-200 status; the response status text is included. It means the agent could not determine the Docker/Podman version, so version-gated behavior stays disabled.

Source

Thrown at agent/docker.go:727

	// Best-effort startup probe. If the engine is not ready yet, getDockerStats will
	// retry after the first successful /containers/json request.
	_, _ = manager.checkDockerVersion()

	return manager
}

// checkDockerVersion checks Docker version and sets goodDockerVersion if at least 25.0.0.
// Versions before 25.0.0 have a bug with one-shot which requires all requests to be made in one batch.
func (dm *dockerManager) checkDockerVersion() (bool, error) {
	resp, err := dm.client.Get("http://localhost/version")
	if err != nil {
		return false, err
	}
	if resp.StatusCode != http.StatusOK {
		status := resp.Status
		resp.Body.Close()
		return false, fmt.Errorf("docker version request failed: %s", status)
	}

	var versionInfo dockerVersionResponse
	serverHeader := resp.Header.Get("Server")
	if err := dm.decode(resp, &versionInfo); err != nil {
		return false, err
	}

	dm.applyDockerVersionInfo(serverHeader, &versionInfo)
	dm.dockerVersionChecked = true
	return true, nil
}

// ensureDockerVersionChecked retries the version probe after a successful
// container list request.
func (dm *dockerManager) ensureDockerVersionChecked() {
	if dm.dockerVersionChecked {
		return

View on GitHub (pinned to b38fb7dafa)

Solutions

1. Confirm the daemon responds: docker version or curl --unix-socket <sock> http://localhost/version
2. Fix DOCKER_HOST / socket path and permissions so /version returns 200
3. If a proxy sits in front, allow /version unauthenticated
4. Re-check after daemon start; ensureDockerVersionChecked will retry

Example fix

// before
export DOCKER_HOST=tcp://localhost:2375
// after: point at a working socket with permissions
export DOCKER_HOST=unix:///run/user/1000/podman/podman.sock
usermod -aG docker <agent-user>

// verify the daemon answers before starting version-dependent features
out, err := exec.Command("docker", "version", "--format", "{{.Server.Version}}").Output()
// or: curl --unix-socket /var/run/docker.sock http://localhost/version

ok, err := dm.checkDockerVersion()
if err != nil {
    log.Warn("version check failed, assuming no version-gated features", "err", err)
}

When it happens

Trigger: GET /version on the configured socket returns non-200 — daemon restarting (503), proxy interception, wrong socket serving a different API, or an endpoint that requires auth returning 401/403.

Common situations: DOCKER_HOST pointing at a TCP endpoint behind an authenticating proxy; Podman socket with restricted permissions; daemon momentarily unavailable during boot; stale DOCKER_HOST after migrating to a rootless socket path.

Related errors

• no logs in response
• no info in response
• container inspect request failed: %s
• %s - %w - see https://github.com/henrygd/beszel/issues/144
• invalid container id

AI-assisted analysis of henrygd/beszel@b38fb7dafa (2026-08-31). Data as JSON: /api/errors/8f0b68b2a9eb747b. Report an issue: GitHub.