- Create a bootable image of the latest macOS (High Sierra).
- In the meantime, swap the hard disk in the MacBook Pro (a procedure that hardly takes more than 10 minutes on a MacBook with a serviceable hard disk drive such as this one).
- Boot from an external device.
- Launch the installation.
- Go out and run.
Unfortunately, it took at least twice the estimated time and three macOS installation attempts.
Attempt 1: Launching the macOS Installer
The MacBook Pro booted the base system correctly from the external device, but when I launched the installer, it failed with the following message:
This copy of the Install macOS High Sierra.app application is damaged and can't be used to install macOS.
A quick search confirmed that this error frequently appears since macOS Sierra and the workarounds I found are quite imaginative. Apparently, many people thinks the installer is actually broken and are trying to download it again. Fortunately, it didn't take that much time to fix the problem. A post on the Apple website described the same problem (although on Sierra) and its solution (after several calls to Apple customer support, according to the author): deleting the ./Contents/SharedSupport/InstallInfo.plist from the bootable image should do the trick. And it did.
Attempt 2: Launching the macOS Installer
The second attempt looked promising: the installer now launched correctly. Unfortunately, it failed on the second screen with the following message:
The recovery server could not be contacted.
The first thing I do in these cases is open a terminal and perform basic checks. The second check I made caught the problem: the system was reporting January, 1st 2001 as the current date. Therefore, most probably, the HTTPS connection to the recovery server was failing because the certificate check was failing (chances are the validity period of that certificate appeared to be in the future).
I fixed the date using the date command and restarted the macOS installer.
Attempt 3: Finding the Hard Disk Drive
The installer was now working, but it couldn't find any disk to install the system. I quitted the installer (for the third time) and opened Disk Utility. To my surprise, Disk Utility couldn't find any internal disk either. Again, a quick search confirmed the obvious: High Sierra's Disk Utility doesn't recognise unformatted internal drives. I opened the terminal again in order to quickly format the drive:
- First of all, confirm the disk is available and its device name:
$ diskutil list
/dev/disk0 (internal, physical):
- Then, format it to make it available to Disk Utility:
$ diskutil eraseDisk JHFS+ NewDisk GPT disk0
Disk Utility could now see the device. I reformatted it using APFS, restarted the installer again and this time the I successfully made it to the end of the installation.
I never needed to reinstall OS X or macOS on any of the three computers I owned in the last 10 years: this was the first macOS installation from scratch I performed in a very long time. However, the three errors I experienced have three characteristics in common which make this experience unsettling:
- They are obscure and difficult to troubleshoot. I bet most non-tech-savvy user would have to ask for help.
- They have been known for years.
- They are, or seem to be, easily solvable. The date problem, for instance: why wouldn't an installer which requires a working Internet connection not synchronise the current time using NTP?
Come on Apple, you can do better than this.