cannot attach to a stopped container, start it first

Error message

cannot attach to a stopped container, start it first

What it means

inspectContainerAndCheckState (cli/command/container/attach.go:25), used by `docker attach`, inspects the target container and at line 30-31 returns errors.New("cannot attach to a stopped container, start it first") when c.Container.State.Running is false. Attaching requires a live process to stream I/O from, so a stopped/exited container is rejected client-side before the attach API call.

Solutions

Start the container first: `docker start <id>` then `docker attach <id>`.
Use `docker ps -a` to confirm the container's STATUS; if Exited, inspect logs (`docker logs <id>`) to see why it stopped.
For one-shot processes, reconsider attach — use `docker run` (foreground) or `docker logs` instead.
If it exits immediately, fix the entrypoint/command and recreate the container.

Example fix

# before (container is stopped)
docker attach web
# after
docker start web && docker attach web

Defensive patterns

Strategy: validation

Validate before calling

// Check container state before attempting attach:
c, err := cli.Client().ContainerInspect(ctx, id, client.ContainerInspectOptions{})
if err != nil { return err }
if !c.State.Running {
    return fmt.Errorf("container %s is not running; start it first", id)
}

Try / catch

if _, err := inspectContainerAndCheckState(ctx, cli.Client(), id); err != nil {
    if strings.Contains(err.Error(), "cannot attach to a stopped container") {
        // start the container, then retry attach
    }
    return err
}

Prevention

Verify STATUS with `docker ps` before attach.
For one-shot workloads, prefer `docker run` over attach.
Check `docker logs` if the container exited unexpectedly.

When it happens

Trigger: Running `docker attach <id>` against a container whose state is 'exited', 'created', 'dead', or otherwise not Running; attaching to a container that crashed/exited between your check and the call.

Common situations: Container exited immediately (bad entrypoint, missing args); short-lived foreground process already finished; attaching to a container started with -d that has since stopped; race where the container exits right before attach.

Related errors

AI-assisted analysis of docker/cli@4f84911bfe (2026-08-07). Data as JSON: /api/errors/08e2cc79a96600e1. Report an issue: GitHub.

Appendix: source

Thrown at cli/command/container/attach.go:31

	"github.com/moby/sys/signal"
	"github.com/sirupsen/logrus"
	"github.com/spf13/cobra"
)

// AttachOptions group options for `attach` command
type AttachOptions struct {
	NoStdin    bool
	Proxy      bool
	DetachKeys string
}

func inspectContainerAndCheckState(ctx context.Context, apiClient client.APIClient, args string) (*container.InspectResponse, error) {
	c, err := apiClient.ContainerInspect(ctx, args, client.ContainerInspectOptions{})
	if err != nil {
		return nil, err
	}
	if !c.Container.State.Running {
		return nil, errors.New("cannot attach to a stopped container, start it first")
	}
	if c.Container.State.Paused {
		return nil, errors.New("cannot attach to a paused container, unpause it first")
	}
	if c.Container.State.Restarting {
		return nil, errors.New("cannot attach to a restarting container, wait until it is running")
	}

	return &c.Container, nil
}

// newAttachCommand creates a new cobra.Command for `docker attach`
func newAttachCommand(dockerCLI command.Cli) *cobra.Command {
	var opts AttachOptions

	cmd := &cobra.Command{
		Use:   "attach [OPTIONS] CONTAINER",
		Short: "Attach local standard input, output, and error streams to a running container",

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