Tonight after a routine MacOS update (10.13.2) disaster struck and my Mac got stuck in an update boot loop. After a few hours of panic, reading online and trial & error I managed to resolve it. Here’s what I did in the hope it also helps someone else.
From the “MacOS could not be installed on your computer” screen:
- Press and hold “option” key and click restart
- In the “Startup disk selection” screen, use the arrow keys to select your main hard drive (not the MacOS update)
- Wait for your Mac to boot normally
- Download the latest combo update directly from Apple. (this is a full system image, not an incremental update)
- Open and install the update
- Grab a snickers, this will take a while
My environment: 2017 Macbook pro 15” Touch Bar with MacOS 10.13.1 (High Sierra) installed and tried to update to 10.13.2 using the App Store.