How to Reinstall an Earlier Version of mac OS if You Need to If something goes wrong and you need to reinstall your older version of mac OS, here is how you do it.
Power down your Mac, connect the USB drive on the mac OS installer, then start your Mac.
That’s because High Sierra uses an entirely new file system called APFS.
We detailed APFS earlier this year during our prep for the upgrade to i OS 10.3.
Users should take heed though and perform the necessary steps to prep their Macs for the new update.
Creating the install media will take some time, so, monitor the progress bar at the bottom of the Disk Creator window.
When complete, set it aside and go ahead and install mac OS High Sierra when the time comes.
Apart from the under the hood improvements, High Sierra comes with new features that give its predecessor a lot of fit and finish.
In this article, we cover some things you should do before you download and install High Sierra on your Mac.
Immediately hold down the Option key until the boot menu appears. When you arrive at the mac OS Utilities screen select Disk Utility then click Continue Select Macintosh HD or the name of your startup drive then click Erase. This is important because High Sierra modifies the drive making it impossible to even restore from a Time Machine backup. Select Restore from Time Machine Backup then follow the instructions for restoring your backup.