thanos-io/thanos · error

unsupported deduplication func, got

Error message

unsupported deduplication func, got %s

What it means

runCompact switches on conf.dedupFunc; any value other than "penalty" or "" (default) is rejected with this errors.Errorf naming the offending value. This guards against typos and removed dedup algorithms.

Solutions

1. Use --deduplication.func=penalty or omit the flag entirely (default chained merge).
2. Check `thanos compact --help` for supported dedup functions in your version.
3. Grep your deploy manifests for the invalid value and correct it.

Example fix

// before
--deduplication.func=penaltyv2
// after
--deduplication.func=penalty

valid := map[string]bool{"": true, "penalty": true}
if !valid[dedupFunc] {
    return fmt.Errorf("deduplication.func must be empty or penalty, got %q", dedupFunc)
}

When it happens

Trigger: Passing --deduplication.func with an unsupported value, e.g. "penalty-replicaboost", "none", or an algorithm removed in a newer Thanos.

Common situations: Typos of "penalty"; copying flags from documentation for other versions; experimenting with algorithms that were never released.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• unknown sync strategy
• penalty based deduplication needs at least one replica…
• level is bigger then default set of
• get compaction levels
• unrecognized label

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/f377ec446a685b10. Report an issue: GitHub.

Appendix: source

Thrown at cmd/thanos/compact.go:340

	defer func() {
		if rerr != nil {
			cancel()
		}
	}()

	var mergeFunc storage.VerticalChunkSeriesMergeFunc
	switch conf.dedupFunc {
	case compact.DedupAlgorithmPenalty:
		mergeFunc = dedup.NewChunkSeriesMerger()

		if len(dedupReplicaLabels) == 0 {
			return errors.New("penalty based deduplication needs at least one replica label specified")
		}
	case "":
		mergeFunc = storage.NewCompactingChunkSeriesMerger(storage.ChainedSeriesMerge)

	default:
		return errors.Errorf("unsupported deduplication func, got %s", conf.dedupFunc)
	}

	// Instantiate the compactor with different time slices. Timestamps in TSDB
	// are in milliseconds.
	comp, err := tsdb.NewLeveledCompactor(ctx, reg, logutil.GoKitLogToSlog(logger), levels, downsample.NewPool(), mergeFunc)
	if err != nil {
		return errors.Wrap(err, "create compactor")
	}

	var (
		compactDir      = path.Join(conf.dataDir, "compact")
		downsamplingDir = path.Join(conf.dataDir, "downsample")
	)

	if err := os.MkdirAll(compactDir, os.ModePerm); err != nil {
		return errors.Wrap(err, "create working compact directory")
	}

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