A template must be supplied using '-template' when using go-

Error message

A template must be supplied using '-template' when using go-template formatting

What it means

Flag validation error in VarListCommand.validateOutputFlag: when -out go-template is selected, a Go template must also be given via -template; it fires when outFmt is go-template but tmpl is empty (errMissingTemplate).

Source

Thrown at command/var_list.go:299

	// variable paths.
	pList := make([]string, len(vars))
	for i, sv := range vars {
		pList[i] = toPathStr(sv)
	}

	return pList
}

func (c *VarListCommand) validateOutputFlag() error {
	if c.outFmt != "go-template" && c.tmpl != "" {
		return errors.New(errUnexpectedTemplate)
	}
	switch c.outFmt {
	case "json", "terse", "table":
		return nil
	case "go-template":
		if c.tmpl == "" {
			return errors.New(errMissingTemplate)
		}
		return nil
	default:
		return errors.New(errInvalidListOutFormat)
	}
}

View on GitHub (pinned to 482b49bf1a)

Solutions

Supply -template with a valid Go template for list entries
Or switch -output to json/terse/table

Example fix

// before
vault kv list -output=go-template secret/
// after
vault kv list -output=go-template -template='{{ range . }}{{ . }}\n{{ end }}' secret/

Defensive patterns

Strategy: validation

Validate before calling

if outFmt == "go-template" && tmpl == "" {
	return errors.New("-output=go-template requires -template")
}

Try / catch

if err := cmd.validateOutputFlag(); err != nil {
	if strings.Contains(err.Error(), "template must be supplied") {
		// supply a template or fall back to table output
	}
	return err
}

Prevention

Never set -output=go-template in profiles without a default template
Wrap go-template usage in helper scripts that take the template as a required argument
Prefer terse/json in automation

When it happens

Trigger: Running `vault kv list -output=go-template <path>` with no -template flag (c.tmpl == "").

Common situations: Setting -output=go-template in a config/profile while the template is supplied in a different invocation; forgetting the flag when converting from table output.

Understand the failure class

Background: "--flag is required" and "must specify" CLI errors: how missing-required-flag validation works and how to fix it — this error's family across 20 libraries.

Related errors

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/4948ee3f430b13a4. Report an issue: GitHub.