owasp-amass/amass · error

unexpected Meta type: %T

Error message

unexpected Meta type: %T

What it means

This hunter.io plugin handler expects the event's Meta field to be a *et.EmailMeta pointer. If the type assertion fails and Meta is non-nil, the actual email-verification result cannot be applied to the event, so it returns this error naming the concrete unexpected Go type via %T. It is a defensive invariant check against events of the wrong type reaching this handler.

Source

Thrown at engine/plugins/api/hunterio.go:158

	var result responseJSON
	resp, err := http.RequestWebPage(context.TODO(), &http.Request{URL: h.emailVerifierurl + email.Address + "&api_key=" + api})
	if err != nil {
		e.Session.Log().Error(fmt.Sprintf("Failed to make Verify request: %v", err),
			slog.Group("plugin", "name", h.name, "handler", h.name+"-Email-Verification-Handler"))
		return nil
	}

	if err := json.NewDecoder(strings.NewReader(resp.Body)).Decode(&result); err != nil {
		e.Session.Log().Error(fmt.Sprintf("Failed to decode JSON: %v", err),
			slog.Group("plugin", "name", h.name, "handler", h.name+"-Email-Verification-Handler"))
		return nil
	}

	eventMeta, ok := e.Meta.(*et.EmailMeta)
	if !ok {
		if e.Meta != nil {
			return fmt.Errorf("unexpected Meta type: %T", e.Meta)
		}
		return nil
	}
	eventMeta.VerifyAttempted = true

	if result.Data.Status != "unknown" && result.Data.Status != "invalid" &&
		result.Data.Status != "disposable" && result.Data.Status != "accept_all" {
		eventMeta.Verified = true
	}
	return nil
}

func (h *hunterIO) account_type(e *et.Event) (string, error) {
	api, err := support.GetAPI(h.name, e)
	if err != nil || api == "" {
		return "", err
	}

View on GitHub (pinned to 79299dce87)

Solutions

1. Check which event type is routed to this handler and ensure only events carrying *et.EmailMeta reach it.
2. Fix the event subscription/filter so the handler only receives email-related events.
3. Update the handler to accept and branch on the new Meta type if the pipeline intentionally delivers it.
4. Audit the emitting plugin to confirm it sets Meta to *et.EmailMeta for these events.

Example fix

// before
eventMeta, ok := e.Meta.(*et.EmailMeta)
if !ok {
	if e.Meta != nil {
		return fmt.Errorf("unexpected Meta type: %T", e.Meta)
	}
	return nil
}
// after
eventMeta, ok := e.Meta.(*et.EmailMeta)
if !ok {
	if e.Meta != nil {
		return fmt.Errorf("hunterio: unexpected Meta type %T; expected *et.EmailMeta", e.Meta)
	}
	return nil
}

if e.Meta == nil {
	return nil // nothing to verify
}

eventMeta, ok := e.Meta.(*et.EmailMeta)
if !ok {
	// not an email-meta event: skip or log %T
}

if err := handler(e); err != nil {
	if strings.Contains(err.Error(), "unexpected Meta type") {
		// mis-routed event: fix subscription, log and continue
	}
}

When it happens

Trigger: An event is delivered to this handler with Meta set to a concrete type other than *et.EmailMeta (e.g., *et.DNSResponse, *et.FQDN, or another service record), typically from a misconfigured event stream/subscription or a plugin emitting wrongly-typed metadata.

Common situations: Pipeline wiring changes where the hunterio handler is subscribed to event types it does not support; a plugin refactor changes the Meta payload type; shared callback registered for multiple event types without discriminating on Meta.

Understand the failure class

Background: "invalid response format", "malformed payload", "missing data field": when an API returns 200 but the response shape is wrong — this error's family across 23 libraries.

Related errors

• failed to cast the DomainRecord
• failed to cast the IPNetRecord
• failed to cast the TLSCertificate asset
• failed to extract the IPAddress asset
• failed to extract the Service asset

AI-assisted analysis of owasp-amass/amass@79299dce87 (2026-09-06). Data as JSON: /api/errors/dfe0fa2b84341816. Report an issue: GitHub.