open() failed, unable to verify if %q exists; reason: %w

Error message

open() failed, unable to verify if %q exists; reason: %w

What it means

Thrown by the experimental fs module's open() in the init context. After resolving the path against the init CWD, k6 calls fsext.Exists to verify it; if that check itself errors (not 'file missing' - a missing file produces a NotFoundError 'no such file or directory'), the error is wrapped as 'open() failed, unable to verify if %q exists' (internal/js/modules/k6/experimental/fs/module.go:125). The failure is in the underlying filesystem's Stat, and the resolved path is included in the message.

Source

Thrown at internal/js/modules/k6/experimental/fs/module.go:125

	path = strings.TrimPrefix(path, "file://")

	// We resolve the path relative to the entrypoint script, as opposed to
	// the current working directory (the k6 command is called from).
	//
	// This is done on purpose, although it diverges in some respect with
	// how files are handled in different k6 contexts, so that we cater to
	// and intuitive user experience.
	//
	// See #2781 and #2674.
	path = fsext.Abs(initEnv.CWD.Path, path)

	fs, ok := initEnv.FileSystems["file"]
	if !ok {
		return nil, errors.New("open() failed; reason: unable to access the file system")
	}

	if exists, err := fsext.Exists(fs, path); err != nil {
		return nil, fmt.Errorf("open() failed, unable to verify if %q exists; reason: %w", path, err)
	} else if !exists {
		return nil, newFsError(NotFoundError, fmt.Sprintf("no such file or directory %q", path))
	}

	if isDir, err := fsext.IsDir(fs, path); err != nil {
		return nil, fmt.Errorf("open() failed, unable to verify if %q is a directory; reason: %w", path, err)
	} else if isDir {
		return nil, newFsError(
			InvalidResourceError,
			fmt.Sprintf("cannot open %q: opening a directory is not supported", path),
		)
	}

	data, err := mi.cache.open(path, fs)
	if err != nil {
		return nil, err
	}

View on GitHub (pinned to 93accf6570)

Solutions

Check the exact path printed in the message - spelling and case - relative to the script's directory
Verify read permission on the file and every parent directory (chmod/chcon as needed)
If running from an archive, rebuild it from the original script tree instead of editing it by hand

Defensive patterns

Strategy: try-catch

Try / catch

try {
  const f = open(path);
} catch (e) {
  if (/unable to verify if .* exists/.test(e.message)) {
    throw new Error(`stat failed for ${path}: check permissions and archive integrity`);
  }
  throw e;
}

Prevention

Use paths relative to the script file, not the shell CWD
Verify read permissions on the file and parent dirs in CI images
Rebuild archives from sources instead of editing them

When it happens

Trigger: fs.open(path) where Stat on the resolved path fails: permission denied on the file or a parent directory, a corrupted entry inside a k6 archive, or an fsext backend error.

Common situations: Restrictive permissions in hardened containers/CI runners; manually unpacked and repacked k6 archives; case-sensitivity mistakes that surface as stat failures on case-sensitive filesystems.

Related errors

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/3718a36027f7b7ea. Report an issue: GitHub.