thanos-io/thanos · error

level is bigger then default set of

Error message

level is bigger then default set of %d

What it means

compactionSet.levels builds the list of compaction levels up to a requested max level. It refuses when maxLevel indexes past the end of the configured level set (maxLevel >= len(cs)), since there is no such level to slice. The message is a wrap-style plain error with the size of the default set interpolated.

Solutions

1. Lower --max-compaction-level to a value within the default set (0..len-1).
2. Omit --max-compaction-level entirely to use the default.
3. Check the configured compaction set size with compactions.maxLevel() and clamp before calling levels().

Example fix

// before
thanos compact --max-compaction-level=5 ...
// after
thanos compact --max-compaction-level=2 ...  # or omit the flag

conn, err := net.DialTimeout("tcp", addr, 5*time.Second)
if err != nil { return err }
conn.Close()

if errors.As(err, &be) && strings.Contains(err.Error(), "failed to bootstrap capnp writer") { time.Sleep(backoff); return retry() }

When it happens

Trigger: Calling levels(n) (directly or via runCompact with --max-compaction-level) where n is >= the number of entries in the compactionSet (e.g. maxCompactionLevel 5+ on a set of 5 levels).

Common situations: Operators set a too-high --max-compaction-level flag on thanos compact, misunderstanding it as a bucket-wide max level rather than an index into Thanos' default compaction levels.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• get compaction levels
• unknown sync strategy
• penalty based deduplication needs at least one replica…
• unrecognized label
• unsupported format for label

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/eaf97576f92fe112. Report an issue: GitHub.

Appendix: source

Thrown at cmd/thanos/compact.go:78

		2 * 24 * time.Hour,
		14 * 24 * time.Hour,
	}
)

type compactionSet []time.Duration

func (cs compactionSet) String() string {
	result := make([]string, len(cs))
	for i, c := range cs {
		result[i] = fmt.Sprintf("%d=%dh", i, int(c.Hours()))
	}
	return strings.Join(result, ", ")
}

// levels returns set of compaction levels not higher than specified max compaction level.
func (cs compactionSet) levels(maxLevel int) ([]int64, error) {
	if maxLevel >= len(cs) {
		return nil, errors.Errorf("level is bigger then default set of %d", len(cs))
	}

	levels := make([]int64, maxLevel+1)
	for i, c := range cs[:maxLevel+1] {
		levels[i] = int64(c / time.Millisecond)
	}
	return levels, nil
}

// maxLevel returns max available compaction level.
func (cs compactionSet) maxLevel() int {
	return len(cs) - 1
}

func registerCompact(app *extkingpin.App) {
	cmd := app.Command(component.Compact.String(), "Continuously compacts blocks in an object store bucket.")
	conf := &compactConfig{}
	conf.registerFlag(cmd)

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