thanos-io/thanos · error · halt

invalid result block

Error message

invalid result block %s

What it means

Wraps (as a halt-worthy error) the failure of block.GatherIndexHealth_stats over the compacted block's index: the index could not be read or contains out-of-bounds/overlapping series outside accepted limits. Since the output of compaction itself is suspect, the whole compactor halts for manual intervention unless accept-malformed-index is enabled.

Solutions

1. Investigate index health errors for the block
2. Re-run compaction from source blocks
3. Use --accept-malformed-index only deliberately

When it happens

Trigger: Thrown at pkg/compact/compact.go:1324 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/283a2b2829ae1cea. Report an issue: GitHub.

Appendix: source

Thrown at pkg/compact/compact.go:1324

			return false, nil, errors.Wrap(err, "remove tombstones")
		}

		newMeta, err := metadata.ReadFromDir(bdir)
		if err != nil {
			return false, nil, errors.Wrap(err, "read new meta")
		}

		var stats block.HealthStats
		// Ensure the output block is valid.
		err = tracing.DoInSpanWithErr(ctx, "compaction_verify_index", func(ctx context.Context) error {
			stats, err = block.GatherIndexHealthStats(ctx, cg.logger, index, newMeta.MinTime, newMeta.MaxTime)
			if err != nil {
				return err
			}
			return stats.AnyErr()
		})
		if !cg.acceptMalformedIndex && err != nil {
			return false, nil, halt(errors.Wrapf(err, "invalid result block %s", bdir))
		}

		thanosMeta := metadata.Thanos{
			Labels:       cg.labels.Map(),
			Downsample:   metadata.ThanosDownsample{Resolution: cg.resolution},
			Source:       metadata.CompactorSource,
			SegmentFiles: block.GetSegmentFiles(bdir),
			Extensions:   cg.Extensions(),
		}
		if stats.ChunkMaxSize > 0 {
			thanosMeta.IndexStats.ChunkMaxSize = stats.ChunkMaxSize
		}
		if stats.SeriesMaxSize > 0 {
			thanosMeta.IndexStats.SeriesMaxSize = stats.SeriesMaxSize
		}
		newMeta, err = metadata.InjectThanos(cg.logger, bdir, thanosMeta, nil)
		if err != nil {
			return false, nil, errors.Wrapf(err, "failed to finalize the block %s", bdir)

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