My suspicion is that this represents a logic error in displaying the error message - the lack of a 128MiB gap between partitions has been translated into the wrong error message. Since the firmware can't read inside an LVM, Apple decided to start storing its boot loader on the volume that's usually called 'Recovery HD.' The message seems to be saying that this volume is not present, but your output clearly indicates that it is present. The error message itself seems to be referring to the fact that, since Yosemite, OS X has used a type of Logical Volume Management (LVM) by default.

If so, though, the error message you received is less than helpful. I've seen OS X installations and updates fail when such gaps are absent, so this could be the same thing. See Apple's TN2166 document for details, and particularly the 'Partitioning Policy' section. I suspect (but am not certain) that the problem is caused by the fact that OS X likes to see gaps (of at least 128MiB) between most partitions. Output of sudo fdisk /dev/disk0: Disk: /dev/disk0 geometry: 30515/255/63 Output of sudo gpt show -l /dev/disk0: gpt show: /dev/disk0: Suspicious MBR at sector 0Ĥ0 409600 1 GPT part - 'EFI System Partition'Ĥ09640 454699328 2 GPT part - 'Macintosh HD'Ĥ55108968 1269536 3 GPT part - 'Recovery HD'

Output of diskutil list: /dev/disk0 (internal, physical):Ģ: Apple_CoreStorage Macintosh HD 232.8 GB disk0s2ģ: Apple_Boot Recovery HD 650.0 MB disk0s3Ġ: Apple_HFS Macintosh HD +232.5 GB disk1

Where has my boot helper partition disappeared (whatever that is), and how can I reinstall OS X on the partition it was previously installed on without touching the Ubuntu setup? My guess is that the Ubuntu partition is causing this. I have tried restarting my computer but the same error message appears each time. Quit the installer to restart your computer and try again. OS X could not be installed on your computerĪ boot helper partition is required when working with Core Storage. After the installer reboots my computer, I get: I’m upgrading my OS X 10.11 (El Capitan) beta to the GM candidate on my MacBook Pro (last year's model, all original hardware) which has a dual-boot setup with Ubuntu.

Install os x el capitan gm candidate