Viewing Errors and Warnings
Any errors or warnings that occur during a sync will result in a red octagon (error) or a yellow triangle (warning) being shown in the Activity Log or in Previews.

Wherever you see an icon indicating the presence of errors, clicking on that icon will bring up an itemised list of the relevant errors.

Errors are grouped into related error types and help on each error can be obtained by;

  1. Hovering your mouse over the error in the details view.

    This should bring up a tooltip with a brief suggestion about how to resolve the error

  2. Double clicking on the error.

    This will take you to a slightly more detailed help view with information about the error.

Note that some errors will only appear when an attempt is made to modify files. Such errors only appear during the actual sync and will not be shown in a preview.

Common Errors and Warnings

Errors establishing a connection

Occurs when connecting to a folder pair via ssh


  • Unable to resolve hostname
  • SSH could not connect

    Double check that the hostname is correct and that you are connected to the internet.

Permission denied

Occurs when executing a sync (not during preview) in cases where DropSync does not have permission to create or modify files in the destination directory, or it does not have permission to read a file in the source.


  • No permission to create a temporary file at the destination
  • Failed to create top level directory for item
  • Unable to read file. Permission denied
  • Failed to create a directory

    The method of resolving this issue depends on the details of the folder pair setup.

  • Folders shared between Macs via Folder Sharing:

    The main things to watch out for in this case are

    • Is the folder shared as Read & Write for the user on the machine that is running DropSync? This can be enabled by going to System Preferences > Sharing > File Sharing
    • Are you attempting to sync files across different users? As an example, consider a folder shared between two Macs. The user on one computer is called bob and on the other computer it is anne. Problems can arise here because files on one side of the sync will be owned by one user (e.g. bob) and files on the other side are owned by anne. Let's say Anne is running DropSync and attempting to sync with files on Bob's computer. If DropSync discovers a newer version of a file on Anne's side it will attempt to update Bob's copy. This works fine so long as (1) the file is marked as Read and Write for all users on Bob's side and (2) DropSync is configured not to sync ownership, group or permissions
  • Folder Pair is on a remote computer accessed via ssh:

    In this case you will need to set the permissions for the folder pair folder so that they include both reading and writing for the user whose login details are used by DropSync to connect.

  • Folder Pair is a regular folder or file:

    Select the folder in Finder and select File > Get Info using Finder. In the info window that appears, change permissions for the user of DropSync to Read and Write

Unable to delete non-empty directory


  • Unable to delete non-empty directory

This error appears for various reasons when DropSync has been configured to delete files/folders during a sync but is unable to delete a directory. Common reasons for this are:

  • Because there are files in that directory which have been otherwise "protected" from deletion. In this context "protected" typically means that the files have been added to DropSync's exclude list (exclusion filters for files can be setup in Advanced options). When a file is excluded from the sync it will not be modified in any way on either side (including deletion). If this file is inside a directory that would otherwise be deleted then this warning will appear.
  • Because dropsync is attempting to create a symbolic link in place of an existing directory

    The first class of problem can be solved by editing DropSync's Filter Rules.

  • First identify the protected file that is causing the issue. (Note. This file might be a hidden file such as .DS_Store or other system file). Then choose between the following methods:

    • Identify the exclude option which specifies a pattern that would include the protected file. Turn this exclude filter off.
    • Optionally, use the advanced pane to hide but not protect the file. For example if the original exclude was for .DS_Store, add an advanced option like --filter=H .DS_Store.

Unable to create a symbolic link. Another file is in the way


  • Unable to delete non-empty directory
  • could not make way for new symlink

This error appears because dropsync is attempting to create a symbolic link in place of an existing directory


    This requires some manual intervention with your files

  • Typically this problem happens when one side of a sync has a symbolic link with the same name as a directory on the other side. Because DropSync cannot make this change, the easiest option is to do it manually.

  • An alternative solution is to change the way DropSync deals with symbolic links so that it transforms links into their referrent files. You should only do this if the contents under the directory and symbolic link are the same and if you are sure that using real files instead of links is the desired outcome.

Rsync syntax errors


  • Incorrect rsync syntax or usage
  • Unknown rsync option

Occurs when the syntax provided to rsync is incorrect. Common scenarios where this might occur are:

  • System rsync is selected and an option is used (eg -X) that is only compatible with the alternate rsync
  • The folder pair is accessed via ssh and the host computer is running a version of rsync that does not accept the provided option.

    Resolve the error by turning off the offending option using the Advanced configure tab. If the error still occurs please contact support.

Resource busy


  • Failed to move temporary file to final destination. File is busy.

Occurs when a file at the destination is locked because it is being run as an executable or is required by another process.


    Quit all processes that might lock the file.

Skipping non-regular file


  • Skipping non-regular file

Occurs when one of the files being transferred is a non-regular file. These include device files and other special files.


    Non-regular files are often created as part of operating system functions. DropSync should generally not be used to sync or make backups of system files. If you are seeing this error it is worth considering whether DropSync is the right tool for the job.



  • Rsync Terminated
  • Connection unexpectedly closed

Occurs when a sync is prematurely terminated (possibly on purpose by cancelling it) or for some other reason.


    Reconnect to the remote host and rerun the sync.

Skipping unsafe symlink


  • Skipping unsafe symlink

Occurs when one of the files being transferred is a symlink and points to a directory outside the Folder Pair root.


    This error only occurs if the --safe-links option is turned on using Advanced options. If copying the linked file is important, then it may be preferable to transform the unsafe link into its referent file using the --copy-unsafe-links option instead.

Skipping empty symlink


  • Skipping symbolic link with empty link target

Occurs when one of the files being transferred is a symlink and points to an empty path. DropSync will avoid copying these symlinks, which results in this warning being generated.


    Either exclude these dead links using An Exclude rule, or ensure that the links are valid. If these links are unimportant on the destination you can safely ignore this warning.

File vanished


  • File vanished during transfer

At the start of the transfer DropSync generates a file list for the source and destination directories and then compares them. It then proceeds to update all of the files in these lists which require updating at the destination. If, during this process a file is deleted at the source (either by the user or by another program) this warning will be generated.


    Generally, repeating the sync should resolve the issue. If the issue recurs often it is worthwhile considering what programs may causing these unexpected deletions.

Failed to copy metadata


  • Failed to copy metadata

Occurs when the destination filesystem does not support extended attributes.


    The resolution to this issue depends on your goals. If syncing extended attributes is essential then you will need to ensure that the destination folder uses a filesystem (such as HFS+) that supports extended attributes.

Missing file or directory


  • An expected file or directory was missing.

Can occur for a variety of reasons. The most common is that a file or directory has made it into DropSync's include list for a sync, but was deleted before the sync could occur.


    Retry the sync. Contact support if the error persists

Temp Dir Missing at Destination


  • Could not create a temporary file because its parent directory does not exist.

Occurs when a location for temporary files is specified using the --temp-dir option but the location does not exist.


    Ensure that the directory specified using --temp-dir exists

Checksum verification errors


  • Failed to verify updated file
  • Updated discarded ... (Will try again)

Occurs when rsync checks that an updated file at the destination is identical to the file at the source and finds that the two files are not the same. The most likely cause of this error is that the file has been modified at the source during a sync. The first time this occurs, rsync tries the transfer again. If a second failure occurs the update is discarded.


    Ensure that files at the source are not modified during a sync.

IO Errors


  • An error occured while reading the file
  • IO error encountered ... skipping file deletion

Generally occurs if rsync fails to read or write data for a file that it has open.


    Check that the files being copied are not corrupted and that the hard-drive hosting the data is formatted properly.

Timeout Errors


  • IO Timeout
  • SSH connection timed out

May occur if the network is too slow to respond during a sync. In this case the time required to generate file lists can be longer than the timeout value, causing a premature timeout.


    If an rsync timeout value has been set, it may be possible to resolve this error by increasing the timeout value, or setting it to 0 (infinite). The default in DropSync 3 is not to set a timeout.

Missing source directory

Occurs when the folder exists at the destination but not at the source. You may need to sync in the opposite direction first.

Other errors


  • Rsync error
  • Unrecognised output

Please contact support for help with these errors. Please include as much detail as possible about your Folder Pair setup as well as the full text of the errors.