What causes "failed to create current out dir %s: %v" in juicedata/juicefs?

Check/create the `--out-dir` and ensure it is writable by the current user: `mkdir -p && ls -ld `.

failed to create current out dir %s: %v

Error message

failed to create current out dir %s: %v

What it means

`juicefs debug` creates a timestamped output directory under `--out-dir` via `os.MkdirAll`. This error is thrown when directory creation fails, wrapping the path and the underlying OS error (permission denied, path is a file, disk full, etc.).

Source

Thrown at cmd/debug.go:536

	} else {
		if inode != uint64(meta.RootInode) {
			return fmt.Errorf("path %s is not a mount point", mp)
		}
	}

	amp, err := filepath.Abs(mp)
	if err != nil {
		return fmt.Errorf("failed to get absolute path: %v", err)
	}
	timestamp := time.Now().Format("20060102150405")
	prefix := strings.Trim(strings.Join(strings.Split(amp, "/"), "-"), "-")
	if runtime.GOOS == "windows" {
		prefix = strings.ReplaceAll(prefix, ":", "")
	}
	outDir := ctx.String("out-dir")
	currDir := filepath.Join(outDir, fmt.Sprintf("%s-%s", prefix, timestamp))
	if err := os.MkdirAll(currDir, os.ModePerm); err != nil {
		return fmt.Errorf("failed to create current out dir %s: %v", currDir, err)
	}

	if err := collectSysInfo(ctx, currDir); err != nil {
		logger.Errorf("Failed to collect system info: %v", err)
	}

	uid, pid, cmd, err := getCmdMount(amp)
	logger.Infof("mount point:%q pid:%s uid:%s", amp, pid, uid)
	if err != nil {
		return fmt.Errorf("failed to get mount command: %v", err)
	}
	fmt.Printf("\nMount Command:\n%s\n\n", cmd)

	requireRootPrivileges := false
	if (uid == "0" || uid == "root") && os.Getuid() != 0 {
		fmt.Println("Mount point is mounted by the root user, may ask for root privilege...")
		requireRootPrivileges = true
	}

View on GitHub (pinned to c9a67b23e8)

Solutions

Check/create the `--out-dir` and ensure it is writable by the current user: `mkdir -p <out-dir> && ls -ld <out-dir>`.
If a path component is a file, remove/rename it or pick another out-dir.
Free disk space if the wrapped error indicates ENOSPC.
Run with appropriate privileges or choose an out-dir the user can write to (e.g. `$HOME/jfs-debug`).

Example fix

// before
$ juicefs debug --out-dir /root/r /jfs
failed to create current out dir ...
// after
$ mkdir -p ~/jfs-debug && juicefs debug --out-dir ~/jfs-debug /jfs

Defensive patterns

Strategy: validation

Validate before calling

outDir := flagOutDir
if fi, err := os.Stat(outDir); err != nil || !fi.IsDir() {
  if err := os.MkdirAll(outDir, 0o755); err != nil {
    return fmt.Errorf("out-dir %s unusable: %w", outDir, err)
  }
}
if f, err := os.CreateTemp(outDir, ".wtest"); err != nil {
  return fmt.Errorf("out-dir %s not writable: %w", outDir, err)
} else { f.Close(); os.Remove(f.Name()) }

Type guard

null

Try / catch

if err := runDebug(mp); err != nil {
  var perr *fs.PathError
  if errors.As(err, &perr) && errors.Is(perr.Err, os.ErrPermission) {
    // choose a writable out-dir or elevate
  }
}

Prevention

Ensure --out-dir exists and is writable
Don't point --out-dir at an existing file
Check free disk space before collecting debug data

When it happens

Trigger: Running `juicefs debug` where the `--out-dir` (default `./`) does not exist, is not writable, a component of the path is a regular file, or the filesystem is out of space/inodes.

Common situations: Passing `--out-dir /root/reports` as a non-root user; `--out-dir` pointing at an existing file; running from a read-only directory; full disk during incident debugging.

Understand the failure class

Background: mkdir permission denied (EACCES): failed to create directory errors explained — this error's family across 32 libraries.

Related errors

AI-assisted analysis of juicedata/juicefs@c9a67b23e8 (2026-09-06). Data as JSON: /api/errors/000744871d581071. Report an issue: GitHub.