kubernetes/kops · error

unsupported output format: %q

Error message

unsupported output format: %q

What it means

RunGetInstances validates the value of --output against the supported formats (table, yaml, json). The `default` branch of the switch rejects any other value with "unsupported output format: %q". This is pure input validation of the options.Output flag, raised before any rendering happens.

Source

Thrown at cmd/kops/get_instances.go:178

		y, err := yaml.Marshal(asRenderable(cloudInstances))
		if err != nil {
			return fmt.Errorf("unable to marshal YAML: %v", err)
		}
		if _, err := out.Write(y); err != nil {
			return fmt.Errorf("error writing to output: %v", err)
		}
		return nil
	case OutputJSON:
		j, err := json.Marshal(asRenderable(cloudInstances))
		if err != nil {
			return fmt.Errorf("unable to marshal JSON: %v", err)
		}
		if _, err := out.Write(j); err != nil {
			return fmt.Errorf("error writing to output: %v", err)
		}
		return nil
	default:
		return fmt.Errorf("unsupported output format: %q", options.Output)
	}
}

func instanceOutputTable(instances []*cloudinstances.CloudInstance, out io.Writer) error {
	fmt.Println("")
	t := &tables.Table{}
	t.AddColumn("ID", func(i *cloudinstances.CloudInstance) string {
		return i.ID
	})
	t.AddColumn("NODE-NAME", func(i *cloudinstances.CloudInstance) string {
		node := i.Node
		if node == nil {
			return ""
		} else {
			return node.Name
		}
	})
	t.AddColumn("STATUS", func(i *cloudinstances.CloudInstance) string {

View on GitHub (pinned to 4c8573c808)

Solutions

1. Pass one of the supported values: `kops get instances -o table|yaml|json`.
2. Check spelling and case — the match is exact lowercase.
3. Run `kops get instances --help` to see the accepted values.
4. In scripts, validate the format variable before invoking the CLI.

Example fix

// before
kops get instances -o JSON
// after
kops get instances -o json

case "$OUTPUT" in
  table|yaml|json) ;;
  *) echo "invalid -o '$OUTPUT'; use table|yaml|json" >&2; exit 2 ;;
esac

if err := runKops("get", "instances", "-o", format); err != nil {
	if strings.Contains(err.Error(), "unsupported output format") {
		return fmt.Errorf("format %q not supported: use table|yaml|json", format)
	}
	return err
}

When it happens

Trigger: `kops get instances -o xml`, `-o csv`, `-o JSON` (case-sensitive matching), or any misspelled/empty format string that does not equal "table", "yaml", or "json".

Common situations: Typo in a script's -o flag; assuming case-insensitive formats (JSON vs json); copying a flag value from another tool that supports more formats; automation templates built for a different kOps version.

Understand the failure class

Background: "unknown output mode", "invalid value for flag", "expects true/false": fixing invalid flag value errors in CLI tools — this error's family across 24 libraries.

Related errors

• unknown output format: %q
• unsupported output type %q
• --name is required
• cannot specify --cert with "all"
• cannot use both --admin and --user

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/0fc50812a999bf7f. Report an issue: GitHub.