since upgrading to El Capitan, every time my machine tries to make a backup to my Time Capsule, it prompts me with the aforementioned message.

after researching and finding not much, I decided to blow away my long history of backups and create a new one as suggested. the backup succeeded but the second time it tried to do a backup it failed again.

so now I have to create a brand new backup (of the whole disk) every time I want to make a backup?

this worked fine on Yosemite!


  • I have a similar problem as well. Have you been experiencing network intermittency with your computer during TM backups? My question is here: apple.stackexchange.com/q/227875/162909 Commented Feb 24, 2016 at 11:57
  • There's always the possibility that the Time Capsule's storage is failing. I don't own one so I don't know how to test it - but that would be my first port of call.
    – Tetsujin
    Commented Feb 24, 2016 at 19:42
  • it's not a network intermittency issue. I get the same error message if I plug my laptop into the Time Capsule directly (wired). and it's not a problem with the TC either. I have other MBPs that back up to it (not upgraded to El Capitan) that work just fine. this is an El Capitan problem
    – ekkis
    Commented Feb 25, 2016 at 8:24
  • I'm getting the same thing trying to back up to a Drobo 5N. Interesting to hear it's also happening with a Time Capsule.
    – SSteve
    Commented Mar 27, 2016 at 18:44
  • I'm having this issue over a Synology NAS, and it's making me worried about my NAS itself; but all the verification tools available there seem to be happy as a clam … I wish someone could dig up some information about what actually causes this error (corrupted files, or metadata? Something to do with permissions or x-attrs?), so I could manually fix it. Commented Aug 9, 2016 at 19:14

1 Answer 1


so the problem was Apple's after all. they never admitted there was a problem but the latest firmware upgrade for the Time Capsule fixed the problem. it hasn't failed to back up even once since the upgrade

  • What firmware version are you using that you think fixes it? You should be able to check from AirPort Utility. Commented May 4, 2017 at 14:20
  • I'm using version 7.7.8
    – ekkis
    Commented May 6, 2017 at 2:20

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