Mountee.app
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Troubleshooting

Fix the most common Mountee and NTFS mounting problems on macOS, from a disabled extension to dirty volumes.

Updated November 14, 2026 Verified against release 0.2.0

Start with the symptom. Most failures fall into one of four groups: the extension is not enabled, the volume is dirty or hibernated, a stale copy of the app is registered, or the disk is not visible to macOS at all.

Quick checks

# Does macOS see the disk and its partitions?
diskutil list

# What does macOS know about the NTFS partition?
diskutil info /dev/diskXsY

# Is the volume currently mounted, and how?
mount | grep -i ntfs

# What extension state does Mountee report?
/Applications/MacNTFS.app/Contents/MacOS/MacNTFS --extension-status

Replace diskXsY with the identifier from diskutil list.

“File system extension not found” or the module never loads

Cause: the extension is not registered, or it is not enabled for the current user.

Check:

pluginkit -m -p com.apple.fskit.fsmodule -vv

The Mountee module appears as com.github.alvarolorentedev.macntfs.ntfsmodule with the path to NTFSModule.appex.

Fix:

  1. Launch Mountee once.
  2. Press Enable File System Extension.
  3. If that fails, enable it in System Settings → General → Login Items & Extensions → File System Extensions.
  4. Run --extension-status again.

On macOS 26, a system bug could prevent the System Settings toggle from enabling third-party FSKit modules. Use the app’s enable button. macOS 27 fixes the bug.

“extension: Not registered” while pluginkit lists the module

Cause: another copy of the app is registered — an old download, a local build, or a checkout. Plug-in registration is per bundle identifier, and the stale path can win.

Check:

pluginkit -m -i com.github.alvarolorentedev.macntfs.ntfsmodule -vv

Compare the reported Path with the app you are launching.

Fix (advanced):

pluginkit -r <stale-NTFSModule.appex>
pluginkit -a /Applications/MacNTFS.app/Contents/Extensions/NTFSModule.appex
pkill -9 -f NTFSModule.appex
/Applications/MacNTFS.app/Contents/MacOS/MacNTFS --enable-extension

Only remove registrations that point at copies you control. If you are unsure, collect diagnostics first.

Writes fail with “Read-only file system”

Cause: the volume is dirty or hibernated by Windows, so Mountee refused read/write and mounted it read-only. A read-only mount request produces the same message.

Check:

log show --last 10m --predicate 'subsystem == "com.github.alvarolorentedev.macntfs.ntfsmodule"'

Notice-level messages include the task options and the downgrade reason.

Fix: boot Windows, let it check the disk, and shut down fully. Disable Fast Startup or hibernation if you need to remove the lock. Then reconnect and mount read/write again.

Do not force write access to a dirty NTFS volume.

“mount: Module … is disabled!”

Cause: the per-user FSKit enablement list does not contain the Mountee module.

Fix: use the app’s Enable File System Extension button, or:

/Applications/MacNTFS.app/Contents/MacOS/MacNTFS --enable-extension

The app must be launched from a normal, non-sandboxed app context for this to work.

The app or extension is killed (exit 137, “Launchd job spawn failed”)

Cause: restricted FSKit entitlements with an ad-hoc or profile-less signature. AMFI kills the process.

Fix: install the signed and notarized release from GitHub. An unsigned local build cannot enable the restricted FSKit extension. This is expected security behavior, not a Mountee bug.

Disk Utility says the volume failed to mount (status 0xC05C)

Cause: on macOS 27, Disk Arbitration’s mount path refuses third-party FSKit modules. Mountee detects this and falls back to the validated mount -F path automatically.

Fix: none needed if Mountee successfully mounted the volume. Listing, unmount, and eject continue to use Disk Arbitration.

If diskarbitrationd logs FSKit check of resource exited with error ... Code=45 and the Mountee fallback also fails, collect the diagnostics report and open an issue.

The volume is not visible at all

This is usually below the Mountee layer.

  1. Reconnect the cable and try another port.
  2. Open System Information → USB or Thunderbolt and confirm the device appears.
  3. Check diskutil list for the disk.
  4. Try another Mac or a Windows PC.
  5. Listen for unusual clicking or spin-up sounds. Stop using a failing drive and recover data first.

If macOS cannot see the block device, no filesystem driver can mount it.

Extension stops reloading new builds

Cause: ExtensionKit can keep an extension process alive after unmount.

Fix (development and advanced troubleshooting):

pkill -9 -f NTFSModule.appex

Then mount again. Regular users should not need this.

Collect diagnostics before filing an issue

Use Copy Diagnostics in the menu bar window, or:

/Applications/MacNTFS.app/Contents/MacOS/MacNTFS --diagnostics ~/Desktop/mountee-diagnostics.txt

The report includes extension state, fskitd/fskit_agent liveness, registered FSKit modules, the NTFS mount table, and detected volumes. Review it for sensitive names before posting publicly.

Open an issue at github.com/alvarolorentedev/mountee/issues.