docker/cli · error

you cannot start and attach multiple containers at once

Error message

you cannot start and attach multiple containers at once

What it means

Raised in RunStart for `docker start` when attach mode is requested (--attach/-a or --interactive/-i) with more than one container argument. Attaching hijacks a single bidirectional stream to one container's stdio and wires up TTY/signal forwarding, which cannot be multiplexed across containers, so the CLI enforces exactly one container in this mode.

Source

Thrown at cli/command/container/start.go:86

//nolint:gocyclo
func RunStart(ctx context.Context, dockerCli command.Cli, opts *StartOptions) error {
	ctx, cancelFun := context.WithCancel(ctx)
	defer cancelFun()

	detachKeys := opts.DetachKeys
	if detachKeys == "" {
		detachKeys = dockerCli.ConfigFile().DetachKeys
	}
	if err := validateDetachKeys(detachKeys); err != nil {
		return err
	}

	switch {
	case opts.Attach || opts.OpenStdin:
		// We're going to attach to a container.
		// 1. Ensure we only have one container.
		if len(opts.Containers) > 1 {
			return errors.New("you cannot start and attach multiple containers at once")
		}

		// 2. Attach to the container.
		ctr := opts.Containers[0]
		c, err := dockerCli.Client().ContainerInspect(ctx, ctr, client.ContainerInspectOptions{})
		if err != nil {
			return err
		}

		// We always use c.ID instead of container to maintain consistency during `docker start`
		if !c.Container.Config.Tty {
			sigc := notifyAllSignals()
			bgCtx := context.WithoutCancel(ctx)
			go ForwardAllSignals(bgCtx, dockerCli.Client(), c.Container.ID, sigc)
			defer signal.StopCatch(sigc)
		}

		options := client.ContainerAttachOptions{

View on GitHub (pinned to e9452d6e78)

Solutions

1. Drop -a/-i to start all containers detached: docker start ctr1 ctr2, then follow one with docker logs -f
2. Start and attach to just one container per command: docker start -a ctr1
3. To watch output of several containers, start them detached and use docker logs -f per container (or docker compose up)

Example fix

# before
docker start -a web db cache
# after
docker start web db cache
docker logs -f web

When it happens

Trigger: `docker start -a ctr1 ctr2`, `docker start -i ctr1 ctr2 ctr3` — opts.Attach or opts.OpenStdin true with len(opts.Containers) > 1. Without -a/-i, starting multiple containers at once is fine.

Common situations: Scripts that expand a list of containers into `docker start -a $list`; users adding -a out of habit when bulk-restarting stopped containers; confusion with docker-compose which can stream logs from many services at once.

Related errors

• valid streams are STDIN, STDOUT and STDERR
• cannot attach to a stopped container, start it first
• cannot attach to a paused container, unpause it first
• cannot attach to a restarting container, wait until it is ru
• destination can not be empty

AI-assisted analysis of docker/cli@e9452d6e78 (2026-08-01). Data as JSON: /data/errors/d3b55a67dd894a34.json. Report an issue: GitHub.