thanos-io/thanos · error

parsing replica header

Error message

parsing replica header: %w

What it means

The wrap text accompanying the replica-header parse failure in handleV1HTTP — the underlying strconv error is wrapped with this message (including %w) so callers see both the raw parse error and that it came from parsing the replica header.

Solutions

1. Inspect the wrapped strconv error for the offending value.
2. Fix the header to a valid unsigned integer.

When it happens

Trigger: Thrown at pkg/receive/handler.go:698 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/67627b02f9226854. Report an issue: GitHub.

Appendix: source

Thrown at pkg/receive/handler.go:698

	for _, i := range wreq.Timeseries {
		hs += len(i.Histograms)
		ts += len(i.Samples)
		es += len(i.Exemplars)
	}
	w.Header().Set("X-Prometheus-Remote-Write-Samples-Written", fmt.Sprintf("%d", ts))
	w.Header().Set("X-Prometheus-Remote-Write-Histograms-Written", fmt.Sprintf("%d", hs))
	w.Header().Set("X-Prometheus-Remote-Write-Exemplars-Written", fmt.Sprintf("%d", es))
}

func (h *Handler) handleV1HTTP(ctx context.Context, w http.ResponseWriter, r *http.Request, wreq *prompb.WriteRequest, tLogger log.Logger, tenantHTTP string, requestLimiter requestLimiter) error {
	var err error

	rep := uint64(0)
	// If the header is empty, we assume the request is not yet replicated.
	if replicaRaw := r.Header.Get(h.options.ReplicaHeader); replicaRaw != "" {
		if rep, err = strconv.ParseUint(replicaRaw, 10, 64); err != nil {
			http.Error(w, "could not parse replica header", http.StatusBadRequest)
			return fmt.Errorf("parsing replica header: %w", err)
		}
	}

	// Exit early if the request contained no data. We don't support metadata yet. We also cannot fail here, because
	// this would mean lack of forward compatibility for remote write proto.
	if len(wreq.Timeseries) == 0 {
		// TODO(yeya24): Handle remote write metadata.
		if len(wreq.Metadata) > 0 {
			// TODO(bwplotka): Do we need this error message?
			level.Debug(tLogger).Log("msg", "only metadata from client; metadata ingestion not supported; skipping")
			return nil
		}
		level.Debug(tLogger).Log("msg", "empty remote write request; client bug or newer remote write protocol used?; skipping")
		return nil
	}

	if !requestLimiter.AllowSeries(tenantHTTP, int64(len(wreq.Timeseries))) {
		http.Error(w, "too many timeseries", http.StatusRequestEntityTooLarge)

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