I am trying to backup my old iPhone 7 to my Mac, so that I can restore it to the new iPhone XS. iTunes keeps giving me an error stating Unable to backup due to insufficient space on the computer. The iPhone that I am trying to back up is 128 GB capacity (with 70 GB free, and I have 128 GB free on my Mac.

What's the probable problem here? Software on all of my devices are up-to-date (macOS Mojave on my Mac and iOS 12.1 on the iPhones).

  • can we see the numbers you are talking about diskutil list
    – Ruskes
    Nov 11, 2018 at 5:52
  • @Buscar웃 Here you go - imgur.com/a/oqISHZB
    – Cruise5
    Nov 11, 2018 at 6:02
  • thank you, that looks fine, not try the About this Mac > Storage to see the result there
    – Ruskes
    Nov 11, 2018 at 6:22
  • @Buscar웃 I already added the about this mac > storage pic in the previous imgur link
    – Cruise5
    Nov 11, 2018 at 6:30
  • sorry I missed that. it says you only have 17 GB left, and you want to transfer 58GB from iPhone. That does not work. So where did you see the 128GB free space ?
    – Ruskes
    Nov 11, 2018 at 6:33

2 Answers 2


According to your information provided

You have 17 GB free space on the Disk.

enter image description here

You also have 128 GB of which 111 GB can be purged (freed).

To purge go to About this Mac > Storage > Manage

enter image description here

Decide what to do by following the instructions.

  • would purging delete any important files ? what data is occupied in the 111 gb purge ?
    – Cruise5
    Nov 11, 2018 at 6:54
  • 1
    @Cruise5 But Disk Utility and Terminal still show not enough space? Have you considered thinning local snapshots?
    – Redarm
    Nov 11, 2018 at 22:21
  • 3
  • 1
    @Redarm Thanks, I think that was the main problem. The time machine snapshots. I used some commands from that page and also from this: thagomizer.com/blog/2018/03/27/… Itunes is finally backing up now.
    – Cruise5
    Nov 11, 2018 at 23:44
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    Thinning should be automatic, but there seem to be issues, especially with Virtual Machines in play.
    – Redarm
    Nov 11, 2018 at 23:57

Check out this post on reddit. This worked for me.. The problem for me was happening because time machine was in the middle of a backup so the available space was being taken by time machine, but it was showing empty everywhere else.


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