Reinstall MacOS Mojave

Reinstall macOS Mojave

The new macOS update, Catalina, has some major changes for mac-users. Apple has gone away with 32-bit app support and COMPLETELY reconfigured how they configure their drivers (for USB, ethernet, etc.). Drivers are now outside the kernel on a level called "user mode." Big thing for us is that when you plug in the Beaglebone Black (BBB), your computer will no longer recognise the device on its network (ie you cannot ssh onto the BBB).

There are ways around this: installing a virtual machine, trashing your Mac for Linux or reinstalling macOS Mojave. This guide walks you through how to install your old OS.

1) Hope you have a TimeMachine backup from before Catalina...

-- You will need a TimeMachine backup from before Catalina, as backups in the new OS will be incompatible with Mojave -- Use OneDrive/Google Drive/GitHub to save important files and documents remotely

2) Create USB Bootable for macOS Mojave

-- You must have a USB of at least 8 GB -- Follow instructions from here: https://support.apple.com/en-gb/HT201372 -- You can erase and format your USB drive in Disk Utility. Find this application in Finder

3) Erase your hard disk

-- Restart your computer with the USB drive plugged in -- Hold down Command + R when the Apple logo appears -- When the menu appears, DO NOT CLICK "Reinstall macOS." Open disk utility (last option), select "Macintosh HD" and erase -- Once erased, continue to boot from startup disk and no disk should appear -- Your Mac should continue and restart again. Once it restarts, there should be an option "Reinstall macOS," this time, it should be Mojave (from the USB drive). -- Reinstall and continue as normal. Restore from TimeMachine backup and you're back to normal!

This procedure is very risky, so it is best to have a safe backup of your data. Proceed at your own risk.