thanos-io/thanos · warning

res.GetWarning()

Error message

res.GetWarning()

What it means

metadataServer.Send is the streaming response sink; when the response carries a Warning string instead of data, it records that warning into srv.warnings via errors.New(res.GetWarning()). It surfaces upstream warnings from the metadata service to the caller.

Solutions

1. Inspect srv.warnings after the call completes to see what was degraded
2. Fix the underlying store error described in the warning text
3. Use PartialResponseStrategy_ABORT if partial results with warnings are unacceptable

metadata, warnings, err := proxy.MetricMetadata(ctx, req)
if err == nil {
    for _, w := range warnings {
        log.Printf("metadata warning: %v", w)
    }
}

When it happens

Trigger: The metadata stream delivers a MetricMetadataResponse with a non-empty warning field, typically generated when a downstream store error was downgraded under PartialResponseStrategy_WARNING.

Common situations: Partial metadata results because one store shard failed; timeouts on part of the metadata scan reported as warnings.

Related errors

• sending metadata warning to server
• %s
• empty exemplars data
• Unknown
• no metadata

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/bf35ef90409190cf. Report an issue: GitHub.

Appendix: source

Thrown at pkg/metadata/metadata.go:79

type metadataServer struct {
	// This field just exist to pseudo-implement the unused methods of the interface.
	metadatapb.Metadata_MetricMetadataServer
	ctx context.Context

	metric string
	limit  int

	warnings    annotations.Annotations
	metadataMap map[string][]metadatapb.Meta
	mu          sync.Mutex
}

func (srv *metadataServer) Send(res *metadatapb.MetricMetadataResponse) error {
	if res.GetWarning() != "" {
		srv.mu.Lock()
		defer srv.mu.Unlock()
		srv.warnings.Add(errors.New(res.GetWarning()))
		return nil
	}

	if res.GetMetadata() == nil {
		return errors.New("no metadata")
	}

	// If limit is set to 0, we don't need to add anything.
	if srv.limit == 0 {
		return nil
	}

	srv.mu.Lock()
	defer srv.mu.Unlock()
	for k, v := range res.GetMetadata().Metadata {
		if metadata, ok := srv.metadataMap[k]; !ok {
			// If limit is set and it is positive, we limit the size of the map.
			if srv.limit < 0 || srv.limit > 0 && len(srv.metadataMap) < srv.limit {

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