How to Create a USB Bootable MediaStep 1. Install and run EaseUS Data Recovery Wizard for Mac on another Mac computer, and select "File > Create Bootable USB". Then, choose a USB drive to create the bootable disc.
If you find out High Sierra is not to your liking, you will need an easy way to downgrade. Having a bootable copy of macOS Sierra on hand can help. There are multiple ways to create a bootable copy of macOS, the easiest is Disk Creator by MacDaddy.io. All you need is an empty 8 GB thumb drive or larger and a copy of the macOS app you can download from the App Store.
How to create a bootable macOS High Sierra installation drive
If, like a friend of mine, you find yourself needing to install a fresh copy ofmacOS Sierra on an older Mac, and you want to create a bootable USB flash driveto hold the installer using createinstallmedia, a quick bit of Googling startsto turn up numerous threads like this.
tl;dr: In late 2019, Apple published an updated macOS Sierra installer whichbroke the ability to create bootable installation media, failing with an errorlike /Volumes/XYZ is not a valid volume mount point. 2ff7e9595c