My MacBook (10.13.6) is backing up via Time Machine to two separate NAS (Synology). This has worked fine for almost a year now, having Time Machine selecting one destination after the other.

Since yesterday however I have the problem, that the backup to one NAS can't be finished. The message is:

Time Machine did not back up because the backup disk was previously encrypted but is no longer encrypted.

The backups have always been encrypted and I didn't change this. Only thing I can imagine is that it has something to do with an update from 10.13.5 to 10.13.6. I think I did this after the last successful backup (as it's stated in the Time Machine dialog).

Peaking into the MyMac.sparsebundle folder on the NAS I see a difference here:

The folder with still working backup has a file token of size 119.5 KB while the one from the broken backup has 0 size.

How to fix this?

  • Did you find a way to solve this? I have the same issue since a week...
    – el-flor
    Aug 14 '19 at 20:43
  • Nope, unfortunately not. Since I have 2 backups, I just started a new one on the "broken" NAS and made a secure backup of the Info.plist and token file this time. I can imagine that it has something to do with the system update. Which OS version are you using btw @el-flor ?
    – Karsten S.
    Aug 16 '19 at 5:37
  • I'm on 10.14.6 right now. I just have one backup, so I can't do much right now. It's really weird.
    – el-flor
    Aug 16 '19 at 6:38
  • I am also having this issue on 10.14.6 since the latest update
    – R_Beagrie
    Aug 16 '19 at 16:14
  • Are you also using a NAS? I guess there's won't be any real support from Apple.
    – Karsten S.
    Aug 17 '19 at 8:43

I deleted something equivalent to "2019-08-04-xxxxxx.inProgress" but that didn't work. Then I found another suggestion that did work for me:

  • Select Disk in Time Machine settings,
  • Remove the disk,
  • Re-add it
  • Tried that as well but didn't work for me.
    – Karsten S.
    Mar 14 '20 at 14:06
  • This worked for me. Apr 27 '20 at 10:34
  • Will that delete my prior backups? May 8 '20 at 23:01

I've just experienced this same issue after the latest supplementary update. I rebooted my Mac and still the same error. I Googled and there are literally two topics on the Internet about this issue with that exact phrase (this topic and one on Apple's website). After some investigating I've managed to resolve this issue.

Turns out my previous backup left a "2019-08-04-xxxxxx.inProgress" in the root of the backup drive. I deleted that file then kicked off a backup from Time Machine and it started backing up the drive immediately without error. It looks like the Mac thought it was being backed up because of that .inProgress file left behind from a previous backup.


  • Plug in your external drive that you use to backup your Mac.
  • Browse to your backup drive with Finder.
  • Look for a "2019-08-xx-xxxxxx.inProgress" file and delete it.
  • Kick off the backup from Time Machine.
  • Yes, created a bug report on Apple. Maybe you found this one.
    – Karsten S.
    Aug 18 '19 at 10:12
  • Did this solve your issue @KarstenS.?
    – el-flor
    Aug 26 '19 at 9:20
  • Nope. As I mentioned above, I deleted the broken backup and started a new one. I have no solution ready to fix it.
    – Karsten S.
    Aug 27 '19 at 10:16

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