gohugoio/hugo · error

transform.Highlight: expects at most 3 arguments

Error message

transform.Highlight: expects at most 3 arguments

What it means

Thrown by transform.Highlight when more than two variadic arguments (i.e. more than three total including the code) are passed (tpl/transform/transform.go:135-136, default case). Highlight accepts the code plus an optional LANG and/or OPTIONS.

Solutions

1. Limit to at most three total arguments: code, lang, options.
2. Combine multiple options into a single options map or string: {{ transform.Highlight .Code "go" (dict "lineNos" "table" "style" "mono") }}.

Example fix

// before
{{ transform.Highlight .Code "go" "lineNos=table" "extra" }}
// after
{{ transform.Highlight .Code "go" (dict "lineNos" "table") }}

{{ transform.Highlight .Code "go" (dict "lineNos" "table") }}

When it happens

Trigger: Calling {{ transform.Highlight .Code "go" "lineNos=table" "extra" }} with a third variadic argument.

Common situations: Adding an extra options argument by mistake; refactoring a call and leaving a stray argument; confusing Highlight with HighlightCodeBlock which takes a context object.

Related errors

• must provide at least one argument
• unmarshal takes 1 or 2 arguments
• failed to detect target data serialization format
• first argument must be a map
• invalid arguments supplied to `time`

AI-assisted analysis of gohugoio/hugo@52c9bd7908 (2026-08-09). Data as JSON: /api/errors/23b879f64ecbd828. Report an issue: GitHub.

Appendix: source

Thrown at tpl/transform/transform.go:136

			opts = args[0]
		} else {
			var arg string
			if arg, err = cast.ToStringE(args[0]); err != nil {
				return "", err
			}
			if strings.Contains(arg, "=") || strings.Contains(arg, ",") {
				opts = arg
			} else {
				lang = arg
			}
		}
	case 2:
		if lang, err = cast.ToStringE(args[0]); err != nil {
			return "", err
		}
		opts = args[1]
	default:
		return "", errors.New("transform.Highlight: expects at most 3 arguments")
	}

	hl := ns.deps.ContentSpec.Converters.GetHighlighter()
	highlighted, err := hl.Highlight(code, lang, opts)
	if err != nil {
		return "", err
	}
	return template.HTML(highlighted), nil
}

// HighlightCodeBlock highlights a code block on the form received in the codeblock render hooks.
func (ns *Namespace) HighlightCodeBlock(ctx hooks.CodeblockContext, opts ...any) (highlight.HighlightResult, error) {
	var optsv any
	if len(opts) > 0 {
		optsv = opts[0]
	}

	hl := ns.deps.ContentSpec.Converters.GetHighlighter()

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