Time Machine Error on ReadyNAS Sparsebundle Could Not Be Accessed (Error 109)

If you’ve been encountering Error 109, “sparsebundle could not be accessed,” when using your ReadyNAS NV+ as your Time Machine backup volume then this fix may work for you. In essence, what we’re going to do is try to repair the corrupted sparsebundle. The sparsebundle can be corrupted by a variety of causes, with users reporting that long file/folder names or names with special characters causing problems. In the most extreme cases, you’ll have to delete your sparsebundle and start a new Time Machine archive fresh. Aside from losing all those Time Machine versions, this can be time consuming and you’ll likely encounter the problem again in the future if you don’t rename your files, folders, and computer name. That is wack, so we’ll try to repair the corruption first and save you some time and, hopefully, prevent the error again.


If you’re lucky, you can go into Disk Utility and repair the sparsebundle directly. To do this:

  1. Mount your sparsebundle in Finder by going to Go > Connect to Server then entering afp://{your ReadyNAS server}. If you normally connect to your ReadyNAS with a specific user or admin account, you’ll need to disconnect first, then connect to the server with the specific ReadyNAS account (i.e. “Connect As”). Otherwise, your ReadyNAS Time Machine volume will not show up. This is the username/password you created in ReadyNAS FrontView > Backups > Time Machine. It is usually something like “ReadyNAS” and a password you specify.
  2. Now we’ll try to use Disk Utility. Go to: Applications > Utilities > Disk Utility.
  3. If your sparsebundle doesn’t show in the left pane–and it probably won’t–drag the sparsebundle from Finder to the left pane in Disk Utility.
  4. Select your sparsebundle in Disk Utility. Hopefully, Disk Utility gives you the option to repair it. If it does, give it a shot and you may not see Error 109 again.


If Disk Utility doesn’t give you the option to repair the sparsebundle or even if it does but you continue to get the connection error, it’s time to move to the command line in Terminal.

  1. In Terminal, manually attach the volume with:

    hdiutil attach -nomount -readwrite -noautofsck -noverify {enter the name of your sparsebundle}.sparsebundle

    This may take a few minutes. The {attach -nomount} parameters here are important because it attaches the volume instead of mounting it. The {-readwrite} parameter makes the image writable (DiskImage tries to attach the volume read-only by default). Finally, the {-noautofsck -noverify} parameters suppress some default auto-checks. We will be doing our checks and repairs manually.

  2. You will now see a list of file systems in the sparsebundle. It will look something like:

    /dev/disk1 Applepartitionscheme
    /dev/disk1s2 Applepartitionmap
    /dev/disk1s2 Apple_HFSX

    The numbers 1 and 2 in the names may be different for you. We are interested in the Apple_HFSX file system. It is usually the last one listed (in this example: /dev/disk1s2).

  3. Now enter this command in Terminal:

    fsck_hfs -rf /dev/disk1s2

    Again, we are entering the Apple_HFSX one. The fsck_hfs command is the HFS file consistency check. The {-rf} parameters rebuild the category tree (r) and force check and repair journaled HFS+ file systems (f). This step may take an hour or so depending on the size of your sparsebundle. Go watch a couple episodes of Tosh.0 while you wait.

If you’re lucky, all the errors will be repaired in your first go and Terminal will display a success message. You may notice some errors output to your terminal screen (“drive contains error, cannot repair”) and your fsck_hfs is interrupted. No worries, some of the errors have been fixed and you just need to repair the remaining errors. If this happens to you, restart your Mac and repeat Steps 1-3. This time the repair process should be much faster and you should see the success message.

Hopefully, this works for you and Error 109 will be banished forever. If this doesn’t work for you then you’ll unfortunately have to delete your sparsebundle and start from fresh. Good luck!