docker/cli · error

conflicting options: cannot specify both --attach and --deta

Error message

conflicting options: cannot specify both --attach and --detach

What it means

Raised in runContainer for `docker run` when --detach/-d is set together with one or more --attach/-a values. Detached mode explicitly clears all attach settings (AttachStdin/Stdout/Stderr), so requesting stream attachment at the same time is contradictory and the CLI rejects it rather than silently ignoring --attach.

Source

Thrown at cli/command/container/run.go:134

	}
	return runContainer(ctx, dockerCLI, ropts, copts, containerCfg)
}

//nolint:gocyclo
func runContainer(ctx context.Context, dockerCli command.Cli, runOpts *runOptions, copts *containerOptions, containerCfg *containerConfig) error {
	config := containerCfg.Config
	stdout, stderr := dockerCli.Out(), dockerCli.Err()
	apiClient := dockerCli.Client()

	config.ArgsEscaped = false

	if !runOpts.detach {
		if err := dockerCli.In().CheckTty(config.AttachStdin, config.Tty); err != nil {
			return err
		}
	} else {
		if copts.attach.Len() != 0 {
			return errors.New("conflicting options: cannot specify both --attach and --detach")
		}

		config.AttachStdin = false
		config.AttachStdout = false
		config.AttachStderr = false
		config.StdinOnce = false
	}

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

	containerID, err := createContainer(ctx, dockerCli, containerCfg, &runOpts.createOptions)
	if err != nil {

View on GitHub (pinned to e9452d6e78)

Solutions

1. Drop --attach if you want a background container: docker run -d image (then use docker logs or docker attach later)
2. Drop --detach if you want to stream output now: docker run -a stdout -a stderr image
3. To background first and view output afterwards, use docker run -d ... followed by docker logs -f <ctr> or docker attach <ctr>

Example fix

# before
docker run -d -a stdout myimage
# after
docker run -d myimage && docker logs -f $(docker ps -lq)

When it happens

Trigger: `docker run -d -a stdout image`, `docker run --detach --attach stderr image` — any run where runOpts.detach is true and copts.attach has at least one stream. (--detach with -i/--tty interactions are handled separately; this check is specifically about --attach.)

Common situations: Compose-like wrappers or shell aliases that always add -d colliding with manually added -a flags; copy-pasted foreground commands with -a getting -d appended for backgrounding; misunderstanding -a as 'attach later', which is actually `docker attach`.

Related errors

• conflicting options: cannot specify both --timeout and --tim
• filtering is not supported when specifying a list of contain
• conflicting options: cannot specify both --network-alias and
• valid streams are STDIN, STDOUT and STDERR
• container prune has been cancelled

AI-assisted analysis of docker/cli@e9452d6e78 (2026-08-01). Data as JSON: /data/errors/fe47b92bf94898f1.json. Report an issue: GitHub.