Cyberduck Mountain Duck CLI

Help / Howto / Mountain Duck / Known Issues

Performance Considerations

To reduce the number of requests to the remote server for mounted volumes, we recommend the following settings when running in Online connect mode.

  • Choose View → Hide Preview (⌘⇧P)
  • Disable View → Show View Options → Show icon preview

Windows Explorer

Choose File Explorer → Folder Options.

  • Check Always show icons, never thumbnails
  • Check Display File Icon on thumbnails
  • Uncheck Show preview handlers in preview pane

Characters to avoid

The following characters should be avoided within file and folder names.

  • : (colon)
  • / (forward slash)
  • \ (backslash)
  • < (less than)
  • > (greater than)
  • : (colon)
  • " (double quote)
  • / (forward slash)
  • \ (backslash)
  • | (vertical bar or pipe)
  • ? (question mark)
  • * (asterisk)

Known Issues

Can only open single PDF in Adobe Acrobat Reader

This is a known bug in Adobe Acrobat Reader when opening documents from a network volume. As a workaround uncheck edit → Preferences… → Security (Enhanced) → Enable Protected Mode at startup.

rsync fails with error

If your server does not accept the creation of . temporary files you might need to add the --inplace when running rsync.

High CPU usage when working with Sublime Text

  • When working with Sublime Text we recommend turning off indexing by adding the following setting to your user preferences in Sublime Text.
    "index_files": false
    "show_git_status": false

Sharing a mounted drive in local network

It is not possible to share a mounted drive within the local network.

Changes from server not immediately visible

The directory listing in or File Explorer may become out of date when another application is adding, removing, or modifying files on the server. You can force File Explorer to refresh the directory listing with F5. On the Mac, choose Reload from the Finder Extension menu. Enable Sync → Index files in Preferences to look for remote file changes every 10 minutes.

Cache uses a lot of disk space

The cache directory is located in %LocalAppData%\Cyberduck\Cache on Windows or in ~/Library/Group Containers/ Support/duck on macOS by default. You can choose another disk for storage of files to be stored in the local cache. You can clear files cached on local disk with the Delete on local disk context menu option.

Missing sync status icons


When you have other applications installed that register a Finder Extension (macOS) for the volume mounted, the status icon may not appear. This has been reported for the following applications:

Please check in System Preferences → Extensions → Finder for other applications that may override the badge icons.

Note If none of those applications are in use, a Finder re-launch can make the badge icons appear again.

Windows Explorer

Windows has a limitation on the number of applications that can register for badge icons in File Explorer. You will need to either uninstall other applications or edit your registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers.

You can find this well documented by Microsoft at Sync icon overlays are missing.

Operating system specific issues does not show files prefixed with . on remote volumes

You can work around this by setting defaults write AppleShowAllFiles YES in a window and restart using  → Force Quit… → Finder → Relaunch. If you are running macOS Sierra (10.12) you can choose ⌘⇧. to toggle files starting with a dot to show in

Original document can't be changed (

Files opened in and edited cannot be saved at the original location but the message "The original document can't be changed, so a duplicate with your changes has been created" is displayed in the title bar. As a workaround, you can set a custom mount point in Preferences → Connection → Mount Location for volumes such as a ~/Volumes/ folder in your home directory.

Enable application icon in Dock

As a utility application with no application windows, no icon is displayed in the Dock but only in the system status bar. If you want to enable the application icon to appear in the Dock set the following property

defaults write io.mountainduck application.dock.icon.enable true

Mounted volumes do not appear on the Desktop

Navigate to volumes using ⌘⇧C in a window or choose Finder → Preferences… → General → Show these items on the desktop: Connected Servers to make the volume appear on the Desktop. Mounted volumes are also listed in the sidebar in Favorites.

Search in (Spotlight)

The Spotlight indexer does not work on remote volumes.

Multiple Mountain Duck Finder Extension processes

The system may launch additional copies of Mountain Duck Finder Extension whenever an Open or Save dialog is displayed. This means there may be multiple copies of the extension running at once, and some may be very short-lived.

Connection Interrupted

It may be that Finder closes the connection because Mountain Duck hasn't answered fast enough on a request of Finder. Although Finder indicates that the server connection is interrupted it isn't as Mountain Duck is still connected to the server.

This is an issue within the operating system that can occur to any network drive.

Solved Issues

Additional ._* files saved on remote volume

The ._* files contain metadata about the file some applications write in addition to the file content. On macOS, this metadata can be stored alongside the file on the filesystem, but on remote volumes, with no metadata support, an auxiliary file is created to contain this information. You can delete metadata on files using xattr -d <filename>.~

As of version 2.1, extended attributes are only saved in a temporary location and not stored on the mounted remote volume. If you want to revert to saving extended attributes to the server, enter in a window

defaults write io.mountainduck fs.filenames.metadata.enable false

If you want to delete metadata files, you can open a window and enter dot_clean -m <folder>

File system driver isn't set up properly

Error: A volume has been accessed for which a file system driver is required that has not yet been loaded

If you get this error message you most likely haven't restarted your system after the installation or update of Mountain Duck. Restart your system to resolve this error. If a system restart doesn't resolve the error try to repair Mountain Duck followed by an application reinstall if this doesn't work either. Additionally, make sure no antivirus software is interfering with the operation of Mountain Duck.

Missing files in Windows Explorer

Windows has a limitation on the maximum path length. It might happen that Mountain Duck exceeds this maximum for long filenames when trying to create placeholders in the local cache. If Mountain Duck is unable to create a placeholder file for a remote file it will not appear in the Windows Explorer listings.

To work around this Windows limitation you can enable long path support in Windows 10 as of version 1607.

  1. Open the Local Group Policy editor (search for Edit Group Policy)
  2. Navigate to Local Computer Policy → Computer Configuration → Administrative Templates → System → Filesystem
  3. Double click the Enable NTFS long paths option and select Enabled

Please refer to Maximum Path Length Limitation.

Multiple File Versions

This is expected behavior within the Online mode as Windows Explorer will first create an empty file followed by writing to the file. Due to this process, you'll see two versions within the versioning on your server. Within the Smart Synchronization mode the empty file won't be synced and the upload is deferred until the file has been fully copied.

Windows Search Indexer

The Windows Search indexer does not work on network drives.

Windows sessions

Mountain Duck requires an interactive user logon session. This separation is done to ensure that each user in a multi-user scenario has access to all available Windows drive letters (otherwise this would be limited to 26 drive letters, shared across all users). Bookmarks are mounted in your regular and elevated user session only - there is no way for other logged-in users or non-interactive services to access your drive. There are no persistent mounts created for anyone to use and cannot work across user sessions - mounts for user A are not visible nor accessible by user B even on the same machine.

Windows Task Scheduler script cannot see the mounted drive

Please make sure you have not checked Run whether user is logged on or not on the scheduled task configuration.

A Windows service has no access to a mounted drive

See Windows sessions above. Services do not have access to logged-in user drives.

Mountain Duck Tooltip persists on screen

You can close that overlay by holding your mouse cursor for about 3 seconds on the Mountain Duck icon within the Tray area.


Hosting Service Providers

A list of known providers that fail to work with Mountain Duck due to interoperability issues.

Third party software

Kaspersky Internet Security

Make sure to uninstall Kaspersky Internet Security with its kernel extensions causing kernel panics prior to mounting a volume.

Eset Cyber Security Pro

Make sure not connections on the loopback interface are blocked.


Be aware that Bitdefender may interfere with connections.

Sophos Endpoint Protection

May interfere with installation.


Backups to Time Machine do not work with volumes mounted from Mountain Duck. Time Machine requires disks mounted using Apple File Protocol (AFP). See Backup disks you can use with Time Machine.

Volumes mounted with Mountain Duck cannot be used by Windows Backup. It can only save backups on destinations that are located within your local system or within your local network.

Bug Reports and Feature Requests

To get help with bugs, feature requests, or other issues please refer to the support page.

Last modified on Jul 17, 2021 at 9:18:31 AM Last modified on Jul 17, 2021 9:18:31 AM

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