gohugoio/hugo · error

sequence bounds out of range [{nv}:]

Error message

sequence bounds out of range [{nv}:]

What it means

After (collections.go:75-77) rejects a negative offset because Go slice bounds cannot be negative. The offending numeric value is interpolated into the message.

Source

Thrown at tpl/collections/collections.go:76

	loc      *time.Location
	sortComp *compare.Namespace
	dCache   *hmaps.Cache[dKey, []int]
	deps     *deps.Deps
}

// After returns all the items after the first n items in list l.
func (ns *Namespace) After(n any, l any) (any, error) {
	if n == nil || l == nil {
		return nil, errors.New("both limit and seq must be provided")
	}

	nv, err := cast.ToIntE(n)
	if err != nil {
		return nil, err
	}

	if nv < 0 {
		return nil, errors.New("sequence bounds out of range [" + cast.ToString(nv) + ":]")
	}

	lv := reflect.ValueOf(l)
	lv, isNil := hreflect.Indirect(lv)
	if isNil {
		return nil, errors.New("can't iterate over a nil value")
	}

	switch lv.Kind() {
	case reflect.Array, reflect.Slice, reflect.String:
		// okay
	default:
		return nil, errors.New("can't iterate over " + reflect.ValueOf(l).Type().String())
	}

	if nv >= lv.Len() {
		return lv.Slice(0, 0).Interface(), nil
	}

View on GitHub (pinned to 52c9bd7908)

Solutions

1. Clamp the offset to >= 0: {{ after (math.Max 0 $n) .Pages }}
2. Guard: {{ if ge $n 0 }}{{ after $n .Pages }}{{ end }}
3. Use (cond (lt $n 0) 0 $n) to coerce

Example fix

// before
{{ after (sub $a $b) .Pages }}
// after
{{ after (math.Max 0 (sub $a $b)) .Pages }}

{{ $n := math.Max 0 $n }}
{{ after $n .Pages }}

When it happens

Trigger: {{ after -1 .Pages }} or any computed offset that goes below zero (e.g. {{ after (sub $a $b) .Pages }} where b > a).

Common situations: Subtracting too much when deriving an offset; user-controlled param passed through without clamping; off-by-one in pagination math.

Related errors

• sequence length must be non-negative
• the number of requested values (%v) must be a non-negative i
• the maximum requested value (%v) must be a non-negative inte
• need at least 2 arguments to append
• can't apply myself (no turtles allowed)

AI-assisted analysis of gohugoio/hugo@52c9bd7908 (2026-08-09). Data as JSON: /api/errors/efc7c643fbd9e4ee. Report an issue: GitHub.