thanos-io/thanos · error

fetch overlaps

Error message

fetch overlaps

What it means

Verification of the overlapped_blocks issue could not even start: fetchOverlaps failed while listing/fetching block metadata from the bucket (listing error, unreadable meta.json, or context cancellation). It is a wrapper that attributes the failure to the overlap-analysis stage, not a finding of overlap itself.

Solutions

1. Inspect the wrapped fetcher error for the failing block ID or list operation.
2. Validate objstore config and credentials; test with 'thanos tools bucket ls'.
3. Find and fix/remove the block with malformed meta.json that breaks metadata parsing.
4. Retry after transient network issues; configure fetcher concurrency/retries appropriately.

Example fix

// before: verifier pointed at wrong bucket/prefix
--objstore.config-file=staging-s3.yaml
// after: correct bucket
--objstore.config-file=prod-s3.yaml

// smoke-test bucket read access before running Verify
iter := bkt.Iter(ctx, "")
_, err := iter.Next(ctx)

if err := (verifier.OverlappedBlocksIssue{}).Verify(ctx, nil); err != nil {
    if strings.Contains(err.Error(), "fetch overlaps") {
        // backoff and retry; inspect wrapped fetcher cause for bad meta.json blocks
    }
}

When it happens

Trigger: ctx.Fetcher (a bucket metadata fetcher) errors: object store unreachable, GetObject/permission failure reading meta.json files, malformed meta.json causing unmarshal failure, or listing errors on the bucket.

Common situations: Misconfigured objstore credentials; a bucket containing blocks with corrupt meta.json; network partition or DNS failure; bucket rate limiting during large listings.

Understand the failure class

Background: 'Something went wrong' / 'Request failed (500)' / 'HTTP error! status: 404' — what failed HTTP requests actually mean and how to find the real cause — this error's family across 28 libraries.

Related errors

• could not sync metas
• unable to create bucket
• unable to sync blocks
• read meta from
• delete block

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/fa2ff36fd9b8c989. Report an issue: GitHub.

Appendix: source

Thrown at pkg/verifier/overlapped_blocks.go:34

	"github.com/thanos-io/thanos/pkg/block"
)

// OverlappedBlocksIssue checks bucket for blocks with overlapped time ranges.
// No repair is available for this issue.
type OverlappedBlocksIssue struct{}

func (OverlappedBlocksIssue) IssueID() string { return "overlapped_blocks" }

func (OverlappedBlocksIssue) Verify(ctx Context, idMatcher func(ulid.ULID) bool) error {
	if idMatcher != nil {
		return errors.Errorf("id matching is not supported")
	}

	level.Info(ctx.Logger).Log("msg", "started verifying issue")

	overlaps, err := fetchOverlaps(ctx, ctx.Fetcher)
	if err != nil {
		return errors.Wrap(err, "fetch overlaps")
	}

	if len(overlaps) == 0 {
		// All good.
		return nil
	}

	for k, o := range overlaps {
		level.Warn(ctx.Logger).Log("msg", "found overlapped blocks", "group", k, "overlap", o)
	}
	return nil
}

func fetchOverlaps(ctx context.Context, fetcher block.MetadataFetcher) (map[string]tsdb.Overlaps, error) {
	metas, _, err := fetcher.Fetch(ctx)
	if err != nil {
		return nil, err
	}

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