gohugoio/hugo · error

too many fields in options parameter to NumFmt

Error message

too many fields in options parameter to NumFmt

What it means

`lang.FormatNumberCustom` (historically aliased as `NumFmt`) takes an options string that, when split by the delimiter, must yield at most three fields: the negative sign, decimal separator, and grouping separator. If the split produces four or more fields, Hugo cannot map them and returns this error.

Source

Thrown at tpl/lang/lang.go:178

			delim = s
		}

		s, err := cast.ToStringE(options[0])
		if err != nil {
			return "", err
		}

		rs := strings.Split(s, delim)
		switch len(rs) {
		case 0:
		case 1:
			neg = rs[0]
		case 2:
			neg, dec = rs[0], rs[1]
		case 3:
			neg, dec, grp = rs[0], rs[1], rs[2]
		default:
			return "", errors.New("too many fields in options parameter to NumFmt")
		}
	}

	exp := math.Pow(10.0, float64(prec))
	r := math.Round(n*exp) / exp

	// Logic from MIT Licensed github.com/gohugoio/locales/
	// Original Copyright (c) 2016 Go Playground

	s := strconv.FormatFloat(math.Abs(r), 'f', prec, 64)
	L := len(s) + 2 + len(s[:len(s)-1-prec])/3

	var count int
	inWhole := prec == 0
	b := make([]byte, 0, L)

	for i := len(s) - 1; i >= 0; i-- {
		if s[i] == '.' {

View on GitHub ↗ (pinned to 8a468df065)

Solutions

1. Reduce the options string to exactly three delimiter-separated fields, e.g. "- , ." for European formatting.
2. If a separator character conflicts with the space delimiter, pass a custom delimiter as the fourth argument, e.g. `{{ lang.FormatNumberCustom 2 12345.67 "-|.|," "|" }}`.
3. Use `lang.FormatNumber` instead if you just want locale-aware formatting for the current language.

Example fix

<!-- before -->
{{ lang.FormatNumberCustom 2 12345.6789 "- . , extra" }}
<!-- after -->
{{ lang.FormatNumberCustom 2 12345.6789 "- . ," }}

{{ $opts := "- . ," }}
{{ if le (len (split $opts " ")) 4 }}{{ lang.NumFmt 2 1234.56 $opts }}{{ end }}

{{ with try (lang.NumFmt 2 1234.56 $opts) }}{{ with .Err }}{{ warnf "NumFmt options invalid: %s" . }}{{ else }}{{ .Value }}{{ end }}{{ end }}

When it happens

Trigger: Calling `{{ lang.FormatNumberCustom 2 12345.67 "- . , x" }}` — an options string with more than three space-delimited fields; or supplying a custom delimiter as the second option that splits the first option string into 4+ parts.

Common situations: Users trying to pass extra formatting flags in the options string, misunderstanding that only `neg dec grp` are supported; a decimal/grouping character containing the delimiter itself (e.g. a space in the format string) causing an unintended extra split; migrating old NumFmt calls with malformed option strings.

Related errors

• invalid precision: %d
• error building site: %w
• failed to detect format from content
• failed to detect target data serialization format
• templates.Defer cannot be used inside a partialCached partia

AI-assisted analysis of gohugoio/hugo@8a468df065 (2026-07-31). Data as JSON: /data/errors/0e1c496d786f15f8.json. Report an issue: GitHub ↗.