lima-vm/lima · error

failed to run %#q on %#q: %#q: %w

Error message

failed to run %#q on %#q: %#q: %w

What it means

WindowsSubsystemPathWithCygpath runs the external cygpath.exe to convert a Windows path to its POSIX/subsystem form. When cygpath exits nonzero AND the failure is not simply 'executable not found' (exec.ErrNotFound / fs.ErrNotExist), the raw combined output and error are wrapped in this error. It signals a real cygpath execution failure (bad arguments, corrupted install, permission issues), not a missing tool.

Source

Thrown at pkg/fsutil/fsutil_windows.go:38

// specific ssh toolchain should use WindowsSubsystemPathWithCygpath, which
// runs that toolchain's own cygpath and respects its fstab.
func WindowsSubsystemPath(ctx context.Context, orig string) (string, error) {
	return WindowsSubsystemPathWithCygpath(ctx, "cygpath", orig)
}

// WindowsSubsystemPathWithCygpath converts a Windows path with the given
// cygpathExe ("cygpath" for PATH, or an absolute path to bind the conversion
// to one Cygwin install). When the cygpath binary is not found it falls back
// to a native conversion of the absolute drive-letter case; a cygpath that
// runs and fails returns its error, and non-drive-letter inputs (UNC, device,
// extended-length) return an error.
func WindowsSubsystemPathWithCygpath(ctx context.Context, cygpathExe, orig string) (string, error) {
	out, err := exec.CommandContext(ctx, cygpathExe, filepath.ToSlash(orig)).CombinedOutput()
	if err == nil {
		return strings.TrimSpace(string(out)), nil
	}
	if !errors.Is(err, exec.ErrNotFound) && !errors.Is(err, fs.ErrNotExist) {
		return "", fmt.Errorf("failed to run %#q on %#q: %#q: %w", cygpathExe, orig, strings.TrimSpace(string(out)), err)
	}

	logrus.WithError(err).Debugf("%#q not found for %#q, attempting native conversion", cygpathExe, orig)

	return windowsSubsystemPathWithoutCygpath(orig)
}

func windowsSubsystemPathWithoutCygpath(orig string) (string, error) {
	// The /c/... form this produces is the MSYS2 and Git-for-Windows
	// convention; stock Cygwin defaults to /cygdrive/c/. Only an absolute
	// drive-letter path ("C:\foo") has a well-defined form here. A
	// drive-relative path ("C:foo") would become an unrelated absolute
	// path, so reject it.
	if !filepath.IsAbs(orig) {
		return "", fmt.Errorf("cannot convert %#q to an MSYS-style path: input is not an absolute drive-letter path", orig)
	}

	// UNC path ("\\server\share\foo") is rejected here.

View on GitHub (pinned to dd909d0973)

Solutions

1. Read the wrapped output in the error to see cygpath's own message and fix the underlying cygpath issue.
2. Verify the cygpath.exe path is correct and the Cygwin/MSYS2/Git-for-Windows installation is intact (run `cygpath -w .` manually).
3. Remove stale duplicate cygpath.exe entries from PATH.
4. If cygpath is genuinely unavailable, note that a not-found error is handled gracefully via the native conversion fallback; this error only fires for other failures.
5. Check permissions/antivirus if exec itself fails.

Example fix

// before
p, err := fsutil.WindowsSubsystemPathWithCygpath(ctx, cygpathExe, orig)
// after
p, err := fsutil.WindowsSubsystemPathWithCygpath(ctx, `C:\Program Files\Git\usr\bin\cygpath.exe`, orig)
if err != nil {
    log.WithError(err).Warn("cygpath failed; verify the installation")
}

if _, err := exec.LookPath(cygpathExe); err != nil {
    return fmt.Errorf("cygpath not available at %q", cygpathExe)
}

p, err := fsutil.WindowsSubsystemPathWithCygpath(ctx, cygpathExe, orig)
if err != nil {
    var ee *exec.ExitError
    if errors.As(err, &ee) {
        log.Errorf("cygpath failed: %v", ee.Stderr)
    }
    return fmt.Errorf("path conversion via cygpath failed: %w", err)
}

When it happens

Trigger: Calling WindowsSubsystemPath (or WithCygpath directly) on Windows when cygpath.exe exists but fails: a broken Cygwin/MSYS2/Git-for-Windows install, wrong cygpathExe path, permission denials, or the target path triggering a cygpath error.

Common situations: Users with partially uninstalled or multiple Cygwin/MSYS2/Git installations on Windows; PATH pointing at a stale cygpath.exe; antivirus blocking process spawn.

Related errors

• expected the depth of the converted host working directory (
• fsutil: Windows path conversion is not supported on this pla
• cannot convert %#q to an MSYS-style path: input is not an ab
• --condition=boot is only supported on macOS
• failed to register instance %#q to start at login: %w

AI-assisted analysis of lima-vm/lima@dd909d0973 (2026-09-01). Data as JSON: /api/errors/3cca6774d21ddacd. Report an issue: GitHub.