mudler/LocalAI · error

router/rerank: policy has empty label

Error message

router/rerank: policy has empty label

What it means

Construction-time panic in NewRerankClassifier: one of the supplied ScorePolicy entries has an empty Label. Labels are both the routing output value and the reranker candidate text anchor, so an empty label is meaningless downstream and is rejected eagerly.

Source

Thrown at core/services/routing/router/rerank.go:48

	budget *lazyBudget
}

// defaultRerankActivationThreshold is the relevance floor a label
// must clear to be considered active. Reranker scores live in [0, 1]
// for cross-encoder / ColBERT heads; 0.5 picks "more positive than
// not on this label."
const defaultRerankActivationThreshold = 0.5

func NewRerankClassifier(policies []ScorePolicy, reranker backend.Reranker, cacheCap int, activationThreshold float64) *RerankClassifier {
	if len(policies) == 0 {
		panic("router/rerank: at least one policy is required")
	}
	if reranker == nil {
		panic("router/rerank: reranker is required (configure router.classifier_model)")
	}
	for _, p := range policies {
		if p.Label == "" {
			panic("router/rerank: policy has empty label")
		}
		if p.Description == "" {
			panic(fmt.Sprintf("router/rerank: policy %q has no description", p.Label))
		}
	}
	if activationThreshold <= 0 {
		activationThreshold = defaultRerankActivationThreshold
	}
	labels := make([]string, len(policies))
	docs := make([]string, len(policies))
	for i, p := range policies {
		labels[i] = p.Label
		docs[i] = p.Description
	}
	return &RerankClassifier{
		reranker:            reranker,
		activationThreshold: activationThreshold,
		labels:              labels,

View on GitHub (pinned to 44413a9d06)

Solutions

1. Find the policy without a label in the router config and give it a non-empty label
2. Check for singular/plural or misnamed keys (label, not labels/name)
3. Add config-time validation to report which policy index is malformed before the panic

Example fix

# before (yaml)
policies:
  - description: "programming questions"
# after
policies:
  - label: code
    description: "programming questions"

for i, p := range policies {
    if strings.TrimSpace(p.Label) == "" {
        return fmt.Errorf("policy %d: empty label", i)
    }
}

func validLabels(ps []ScorePolicy) bool { for _, p := range ps { if p.Label == "" { return false } }; return true }

When it happens

Trigger: A policies list entry missing its label key, or label: "" in YAML; programmatically appending a zero-value ScorePolicy{}; whitespace-only labels after trimming in config.

Common situations: YAML typo (labels vs label, or the field named differently); copy-pasted policy block with the label line accidentally removed; config schema that allows label to be optional.

Related errors

• router/rerank: policy %q has no description
• router/score: policy has empty label
• router/score: policy %q has no description
• router/score: system_prompt_template: %v
• router/rerank: at least one policy is required

AI-assisted analysis of mudler/LocalAI@44413a9d06 (2026-08-15). Data as JSON: /api/errors/f2045b8b26fda46b. Report an issue: GitHub.