I just updated from Yosemite to El Capitan. I have two backups, one being done with Time Machine and one with Carbon Copy Cloner. Both sparsebundles are stored on a NAS (Synology DS213). After the update everything still works as before. I can do backups and verifying them shows them as being there and functional.

However, navigating to the Backup folder on the NAS using Finder shows the sparsebundles as folders, not as sparsebundles. So instead of: Backup.sparsebundle I now have: C33YRS~D

Trying to open them launches Terminal. I restarted the MAC and also the NAS, the sparsebundles are still displayed as folders.

What happened? Does anybody have the same issue? Can I just rename these files back to their original name or is there something else I am missing?

  • What is the native file system on the NAS? What operating system version is browsing the files and showing them his folders? We might have a hard time guessing you're set up without some more details.
    – bmike
    Commented Nov 10, 2015 at 12:12
  • The NAS file system is ext4. The Mac I am browsing with uses El Capitan 10.11.1. When checking the backup folder with a Windows 7 PC I have the same cryptic file names. As I have never checked the backup folder with a Windows PC before, I cannot say if it was always like that. Maybe the names have always been like that, which would mean that the update from Yosemite to El Capitan somehow led to the Mac "losing" the information that these files are actually sparsebundles.
    – Chi
    Commented Nov 10, 2015 at 12:57

2 Answers 2


It seems to be an issue related to AFP/SMB and invalid SMB characters. My two sparsebundles have an asterisk in them, resulting from the computer name. An asterisk seems to be an invalid character in SMB. Everything was fine until the El Capitan update. It seems in this update something changed with the AFP/SMB handling on OSX. I had to disable SMB on my NAS (Synology) to force AFP and to have the proper names displayed.


When you back up to a network volume, Time Machine makes a sparse bundle folder. There aren't any large changes between 10.11 and 10.10 so I doubt the upgrade caused anything. It's likely that you are seeing the band files for the first time or something coincidental to and not caused by the upgrade happened to change the files.

I would open the folder in Finder and see if you can click on the bundle to mount it. Look in Console.app for any errors in mounting the volume or use Disk Utility to verify it. If you are looking at the files in terminal or windows - here is what you should see inside the sparse bundle if things are working correctly and there is no corruption:

mac:~ bmike$ ls -laeO /Volumes/TimeMachineBackups/Mac.sparsebundle 
total 208
drwx------@ 1 mike  staff  - 16384 Nov 10 08:16 .
drwx------  1 mike  staff  - 16384 Nov 10 08:50 ..
-rw-r--r--  1 mike  staff  -   499 Sep 14 14:06 Info.bckup
-rwx------  1 mike  staff  -   499 Sep 14 14:06 Info.plist
drwx------  1 mike  staff  - 16384 Nov 10 07:09 bands
-rw-r--r--  1 mike  staff  -   512 Nov 10 07:58 com.apple.TimeMachine.MachineID.bckup
-rw-r--r--  1 mike  staff  -   512 Nov 10 07:58 com.apple.TimeMachine.MachineID.plist
-rw-r--r--  1 mike  staff  -  1302 Nov 10 08:16 com.apple.TimeMachine.Results.plist
-rw-r--r--  1 mike  staff  - 13523 Nov 10 08:16 com.apple.TimeMachine.SnapshotHistory.plist
-rwx------  1 mike  staff  -     0 Sep 14 14:06 token
mac:~ bmike$ ls -1 /Volumes/TimeMachineBackups/Mac.sparsebundle/bands/ | wc -l

The ls flags are lower case L, lower case A and E, capital O in the first command and the digit 1 in the second. As you can see, the band files should number between 20k and 40k files of odd names to contain the actual filesystem that stores all the backup data.

enter image description here

  • The backup files are fine. I can right click the strangely named folders (C33YRS~D and CHWZJ5~E) in finder and use "Show package contents" to see the bands and everything else (just as in your screenshots). I can mount them and also see the package contents. I can also backup as I could before. But the backup files have been called "Mac.sparsebundle" and "Mac_CCC.sparsebundle" before the update from Yosemite to El Capitan. Now they are called C33YRS~D and CHWZJ5~E without any file extension.
    – Chi
    Commented Nov 10, 2015 at 15:52
  • Strangely enough Carbon Copy Cloner still shows the "old" and "correct" name "Mac_CCC.sparsebundle", but when I try to create a new backup plan I am not able to select the sparsebundle - because it is missing the sparsebundle extension. I guess I will just rename them to the old names and hope nothing breaks.
    – Chi
    Commented Nov 10, 2015 at 15:52
  • Just an update for anybody having the same issue. The sparsebundles are still correctly named when accessing the file system directly through the Synology Web Interface. It only seems that El Capitan is wrongly displaying/interpreting the names. Still investigating where this comes from.
    – Chi
    Commented Nov 10, 2015 at 17:20
  • @Chi I'm surprised anything works if the file names are in capital letters, but perhaps the software that runs on the NAS to trick OS X into thinking it's a viable backup destination is filling in the missing information or acting as a translation layer. Did you ask the vendor if they support the new version of OS X you are running?
    – bmike
    Commented Nov 10, 2015 at 19:03

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