--format is incompatible with human friendly format

Error message

--format is incompatible with human friendly format

What it means

In `docker service inspect`, the `--pretty` and `--format` flags are mutually exclusive — `--pretty` selects the built-in human-readable template while `--format` selects a user-supplied Go template. This error fires at service/inspect.go:37-38 when both flags are set simultaneously (`opts.pretty == true && len(opts.format) > 0`). The check runs in the command's RunE before any API call is made.

Solutions

Remove `--pretty` when using `--format` (they conflict by design)
Remove `--format` when using `--pretty`
Use `--format pretty` (exactly the word) instead of `--pretty` to get human-friendly output without the flag conflict

Example fix

# before
docker service inspect --pretty --format "{{.ID}}" myservice

# after (custom template)
docker service inspect --format "{{.ID}}" myservice

# after (human-friendly)
docker service inspect --pretty myservice

Defensive patterns

Strategy: validation

Validate before calling

// Validate mutual exclusivity before invoking the command
func validateServiceInspectOpts(format string, pretty bool) error {
    if pretty && len(format) > 0 {
        return errors.New("--pretty and --format are mutually exclusive")
    }
    return nil
}

Prevention

Treat --pretty and --format as mutually exclusive in all wrapper scripts
If you have a global --format alias, use `--format pretty` instead of --pretty to avoid the conflict path
Document which output mode each script/alias uses to prevent accidental mixing

When it happens

Trigger: Running `docker service inspect --pretty --format "{{.ID}}" myservice` where both `--pretty` is true and `--format` has a non-empty value. Also triggered if a shell alias or wrapper always appends `--format` and the user adds `--pretty`.

Common situations: A developer has a Docker config or shell alias that sets `--format` globally, then tries to use `--pretty` for a quick human-readable check. Or a CI script hardcodes `--format json` and an operator overrides with `--pretty`.

Related errors

AI-assisted analysis of docker/cli@4f84911bfe (2026-08-07). Data as JSON: /api/errors/5fe0ed38757de63a. Report an issue: GitHub.

Appendix: source

Thrown at cli/command/service/inspect.go:38

type inspectOptions struct {
	refs   []string
	format string
	pretty bool
}

func newInspectCommand(dockerCLI command.Cli) *cobra.Command {
	var opts inspectOptions

	cmd := &cobra.Command{
		Use:   "inspect [OPTIONS] SERVICE [SERVICE...]",
		Short: "Display detailed information on one or more services",
		Args:  cli.RequiresMinArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			opts.refs = args

			if opts.pretty && len(opts.format) > 0 {
				return errors.New("--format is incompatible with human friendly format")
			}
			return runInspect(cmd.Context(), dockerCLI, opts)
		},
		ValidArgsFunction:     completeServiceNames(dockerCLI),
		DisableFlagsInUseLine: true,
	}

	flags := cmd.Flags()
	flags.StringVarP(&opts.format, "format", "f", "", flagsHelper.InspectFormatHelp)
	flags.BoolVar(&opts.pretty, "pretty", false, "Print the information in a human friendly format")

	return cmd
}

func runInspect(ctx context.Context, dockerCLI command.Cli, opts inspectOptions) error {
	apiClient := dockerCLI.Client()

	if opts.pretty {

View on GitHub (pinned to 4f84911bfe)