gohugoio/hugo · error

truncate requires a length and a string

Error message

truncate requires a length and a string

What it means

Thrown by strings.Truncate when no options (the text to truncate) are supplied (tpl/strings/truncate.go:52-54). Truncate's signature is Truncate(s any, options ...any) where s is the length and the first option is the text; calling it with only the length leaves nothing to truncate.

Solutions

1. Provide the text as the second argument: {{ truncate 50 .Title }}.
2. Pipe the text instead: {{ .Title | truncate 50 }}.
3. Optionally add a custom ellipsis as the middle argument: {{ truncate 50 "..." .Title }}.

Example fix

// before
{{ truncate 50 }}
// after
{{ truncate 50 .Summary }}

{{ truncate 50 .Title }}

When it happens

Trigger: Calling {{ truncate 50 }} or {{ 50 | truncate }} with no string argument.

Common situations: Piping a number into truncate expecting it to act on the page content; forgetting the second argument; misreading the docs which list length first.

Related errors

• too many arguments passed to truncate
• ellipsis must be a string
• text must be a string
• invalid arguments supplied to `time`
• length argument must be an integer

AI-assisted analysis of gohugoio/hugo@52c9bd7908 (2026-08-09). Data as JSON: /api/errors/8fd4b9f09596b5dd. Report an issue: GitHub.

Appendix: source

Thrown at tpl/strings/truncate.go:54

type htmlTag struct {
	name    string
	pos     int
	openTag bool
}

// Truncate truncates the string in s to the specified length.
func (ns *Namespace) Truncate(s any, options ...any) (template.HTML, error) {
	length, err := cast.ToIntE(s)
	if err != nil {
		return "", err
	}
	var textParam any
	var ellipsis string

	switch len(options) {
	case 0:
		return "", errors.New("truncate requires a length and a string")
	case 1:
		textParam = options[0]
		ellipsis = " …"
	case 2:
		textParam = options[1]
		ellipsis, err = cast.ToStringE(options[0])
		if err != nil {
			return "", errors.New("ellipsis must be a string")
		}
		if _, ok := options[0].(template.HTML); !ok {
			ellipsis = html.EscapeString(ellipsis)
		}
	default:
		return "", errors.New("too many arguments passed to truncate")
	}

	text, err := cast.ToStringE(textParam)
	if err != nil {

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