Disk Utility in Sierra won't repartition a disk 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.
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.