juicedata/juicefs · error

DumpMeta error: %v

Error message

DumpMeta error: %v

What it means

This message is produced in redisMeta.dump (DumpMeta) as a panic-recovery fallback: if dump panics with a non-error value, it is converted into err = errors.Errorf("DumpMeta error: %v", p) and returned. Callers of DumpMeta therefore see this wrapped message whenever the dump implementation hits an unrecovered panic — a programming/invariant bug in the dump path rather than an ordinary operational failure.

Source

Thrown at pkg/meta/redis.go:4952

		if i != len(entries)-1 {
			bwWrite(",")
		}
		if showProgress != nil {
			showProgress(0, 1)
		}
	}
	bwWrite(fmt.Sprintf("\n%s}\n%s}", strings.Repeat(jsonIndent, depth+1), strings.Repeat(jsonIndent, depth)))
	return nil
}

func (m *redisMeta) DumpMeta(w io.Writer, root Ino, threads int, keepSecret, fast, skipTrash bool) (err error) {
	defer func() {
		if p := recover(); p != nil {
			debug.PrintStack()
			if e, ok := p.(error); ok {
				err = e
			} else {
				err = errors.Errorf("DumpMeta error: %v", p)
			}
		}
	}()
	ctx := Background()
	var lastChangelog int64
	if m.getFormat().ChangeLog {
		lastLog, err := m.rdb.Get(ctx, m.txnLastLog()).Int64()
		if err == nil {
			lastChangelog = lastLog
		}
	}
	zs, err := m.rdb.ZRangeWithScores(ctx, m.delfiles(), 0, -1).Result()
	if err != nil {
		return err
	}
	dels := make([]*DumpedDelFile, 0, len(zs))
	for _, z := range zs {
		parts := strings.Split(z.Member.(string), ":")

View on GitHub (pinned to c9a67b23e8)

Solutions

1. Report the panic (with debug.PrintStack output, which is printed) to JuiceFS with the version and meta type; this path indicates a bug.
2. Capture the stack trace and check release notes for a newer version fixing dump panics; upgrade the client.
3. Work around by taking a Redis RDB/AOF backup instead of a JSON dump if dump is consistently panicking.
4. Verify metadata integrity (gc/repair) in case the panic stems from corrupt records.

// No caller-side validation prevents an internal panic; capture diagnostics:
err := juicefs.Dump(ctx, meta, w, &meta.DumpOption{KeepSecret: false})

if err := juicefs.Dump(ctx, meta, f, opt); err != nil {
    if strings.Contains(err.Error(), "DumpMeta error") {
        logger.Errorf("dump panicked, save stack + version for bug report: %v", err)
        // fall back to engine-native backup (RDB/AOF, SQL dump)
    }
    return err
}

When it happens

Trigger: Running `juicefs dump` (or backup) against a Redis metadata engine when the dump goroutine panics (e.g. nil dereference on an unexpected metadata record shape, index-out-of-range while iterating dumped entries); the deferred recover in redisMeta.dump converts the panic into this returned error.

Common situations: Dumping a volume whose metadata contains records written by a newer incompatible client; corrupted metadata entries; genuine bugs in a specific JuiceFS version's dump code.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• get counter %s
• DumpMeta error: %v
• get %s err: %w
• get dirDataLengthKey err: %w
• get dirUsedInodesKey err: %w

AI-assisted analysis of juicedata/juicefs@c9a67b23e8 (2026-09-06). Data as JSON: /api/errors/cdd7f9c2fdea7934. Report an issue: GitHub.