I recently got a new MacBook Air and used Migration Assistant (henceforth abbreviated as MA) to transfer my stuff from my old MacBook Pro. However, until MA actually worked all the way, I had to abort it and restart both machines three times. This resulted in around 50GB of wasted space in my new macbook (but no extraneous user accounts, as I read elsewhere) that I don't know how to eliminate. I assume there are some cache files that MA creates & uses until the entire migration is complete.

Where can I find these files, to delete the leftover ones from the incomplete migrations?

  • What make you think they are relicts from failed migration attempts?
    – nohillside
    Jun 30, 2012 at 11:15
  • @patrix: That before I started the first migration, the displayed free space was much more than the one displayed before I started the last migration.
    – Lea Verou
    Jun 30, 2012 at 13:33
  • @LeaVerou Was TimeMachine enabled during any of this? If so, what does "About this Mac -> More info -> Storage" say about the current size of Backups?
    – ephsmith
    Jun 30, 2012 at 18:00
  • @ephsmith No, Time Machine was never enabled.
    – Lea Verou
    Jun 30, 2012 at 21:17

2 Answers 2


You could use OmniDiskSweeper (free to download and use) to search for and remove big folders. To find the problematic area fast, run it in parallel on both your macs (to see the differences) and start at the top level.

If you don't want to install additional software, you can start by running du -sg /* on both Macs, drilling down into the directories with the biggest difference and repeating du until you found the problematic files.

  • I've been using the new Mac for over 10 days, so there are differences anyway. Also, I was hoping for an answer that doesn't involve 3rd party software.
    – Lea Verou
    Jun 30, 2012 at 13:34
  • ODS is free actually. And if you are searching for 50 GB, small differences won't matter.
    – nohillside
    Jun 30, 2012 at 19:16

For me it was in /var/folders/zz/, but all you need to do to reclaim space is reboot your computer and it gets deleted automagically for you.

  • This worked for me!!!
    – joshua
    Jan 12, 2022 at 19:30

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