After upgrading to sierra with a clean format and install, I can't partition any disks. When I select a drive (not the partition) and click the partition button, I get this screen. Notice that just about all of the controls are greyed out. I had this problem before and was able to partition and format from the command line - but that's very inconvenient.

How can I unlock this?

BTW, my install was from the pre-release GM, but that should be identical to the final release.

Disk utility partition screen

  • 1
    I'm having similar problems on Sierra - the UI doesn't work as expected and after clcking Apply, success is reported, but nothing has actually changed. It seems Sierra Disk Utility is simply broken. Who needs a disk utility anyway, when Sierra features all these new emojis...
    – ssc
    Commented Dec 13, 2016 at 11:02
  • Update to my comment above: I've found out now that in order to enlarge a partition, you need to delete on "Free Space" and delete that. Disk Utility the "quits unexpectedly", but at least, the partition seems resized now. First Aid reports to have "found corruption" on the hard drive and First Aid needs to be run from Recovery. Rubbish.
    – ssc
    Commented Dec 13, 2016 at 11:08

2 Answers 2


In the Disk Utility Screen, try selecting the next option up. It might be the name of the Mounted Volume. Sometimes if you try to format a Disk nested under another Volume it doesn’t work.

Also try different File Systems, some format troublesome disks better than others. For example try FAT before you try NTFS.


Based on your screenshot, currently the partition map is the selected volume. You won't be able to make changes until you select the larger white area. At that point the + button should be enabled.

If that doesn't work, format the drive and try again.

  • I can't select it, and erasing gives me much fewer options.
    – DAB
    Commented Oct 3, 2016 at 20:21

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .