144 MACWORLD DECEMBER 2019
HELP DESK MAC 911macOS startup partition and not the entire
drive, which contains the macOS Recovery
partition you’re currently using. Fom the
View menu, select Show All Devices.
- Select just the partition or container
with macOS and click the Erase button. - Quit Disk Utility and use Reinstall
macOS from the main recovery window.
It’s possible you’ll hit an error at any
one of these points.
For instance, some readers report
receiving the message: “Secure Disk Erase
Failed—Couldn’t Unmount Disk.” This
happens in a few circumstances, but most of
the time because you’re trying to erase the
entire disk—consult steps 5 and 6 above.
If that doesn’t help, because you’re
trying to erase the entire drive, you can
shift to internet-based macOS Recovery
(go.macworld.com/mcrc), which downloads
the recovery software
temporarily from the
internet and can erase
the entire drive. For
most Macs in recent
years, restart and hold
down Command-
Option-R. (For Macs
running a version of
the operating system
before Sierra, the key
combinations will be
different [go.macworld.
com/kycm].)
In a few moments, you should see a
rotating globe, which indicates your Mac is
pulling down the necessary files over the
Internet. You’ll be prompted at some point
for the name and network password for a
Wi-Fi network, unless you’re connected via
Ethernet to a network.
You should now be able to proceed to
erase the disk in full and reinstall a fresh
copy of macOS..HOW TO TURN ON ICLOUD
PHOTOS WHEN iOS SAYS
YOU CAN’T
If you ever used iTunes on the Mac to sync
photos and albums with iOS, you could
have problems enabling iCloud Photos,
Apple’s synchronization and backup
options for images and videos captured in
and imported into iOS and macOS.