argoproj/argo-workflows · error

unknown output mode: %s

Error message

unknown output mode: %s

What it means

`argo template list` supports only two output formats: the default table (`wide`) and `name`. The command's switch statement falls through to a default case that returns `unknown output mode: %s` when `--output` is set to anything else. Normally the `EnumFlagValue` flag definition rejects bad values at parse time, so this error is a defensive fallback for programmatically-set or manipulated flag values.

Source

Thrown at cmd/argo/commands/template/list.go:66

			wftmplList, err := serviceClient.ListWorkflowTemplates(ctx, &workflowtemplatepkg.WorkflowTemplateListRequest{
				Namespace: namespace,
				ListOptions: &metav1.ListOptions{
					LabelSelector: labelSelector.String(),
				},
			})
			if err != nil {
				return err
			}
			switch listArgs.output.String() {
			case "", "wide":
				printTable(wftmplList.Items, &listArgs)
			case "name":
				for _, wftmp := range wftmplList.Items {
					fmt.Println(wftmp.Name)
				}
			default:
				return fmt.Errorf("unknown output mode: %s", listArgs.output)
			}
			return nil
		},
	}
	command.Flags().BoolVarP(&listArgs.allNamespaces, "all-namespaces", "A", false, "Show workflows from all namespaces")
	command.Flags().VarP(&listArgs.output, "output", "o", "Output format. "+listArgs.output.Usage())
	command.Flags().StringVarP(&listArgs.labels, "selector", "l", "", "Selector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2)")
	return command
}

func printTable(wfList []wfv1.WorkflowTemplate, listArgs *listFlags) {
	w := tabwriter.NewWriter(os.Stdout, 0, 0, 3, ' ', 0)
	if listArgs.allNamespaces {
		_, _ = fmt.Fprint(w, "NAMESPACE\t")
	}
	_, _ = fmt.Fprint(w, "NAME")
	_, _ = fmt.Fprint(w, "\n")
	for _, wf := range wfList {

View on GitHub (pinned to 35bff19146)

Solutions

1. Use a supported output format: omit --output or use -o wide (table) or -o name (one name per line).
2. For machine-readable output use `argo template list -o name` and post-process, or fetch via the API/`kubectl get workflowtemplates -o json`.
3. Check `argo template list --help` for the exact allowed values of --output.

Example fix

// before
argo template list -o json
// after
argo template list -o name   # or: kubectl get workflowtemplates -o json

allowed := map[string]bool{"": true, "wide": true, "name": true}
if !allowed[output] { return fmt.Errorf("output must be wide or name, got %q", output) }

func validTemplateListOutput(o string) bool { return o == "" || o == "wide" || o == "name" }

When it happens

Trigger: Running `argo template list -o json` (or yaml, etc.); constructing the command in tests or code and setting listArgs.output to a value outside {"", "wide", "name"}; older CLI versions or scripts copied from `argo wf list` examples (which support more formats) being reused for templates.

Common situations: Users scripting `argo template list -o json` expecting parity with `argo workflow list -o json`; shell aliases/argument passing mixing up workflow and template subcommands; tests calling the RunE function directly with arbitrary output values.

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 formatter: %s
• unknown kind: %s
• unknown output mode: %s
• requires either selector or workflow
• Multiple archived workflows found with name '%s': %s (Crea

AI-assisted analysis of argoproj/argo-workflows@35bff19146 (2026-09-03). Data as JSON: /api/errors/a4c5a2f522194a1d. Report an issue: GitHub.