To create a bootable flash drive you need a USB drive with a capacity of 8 gigabytes and a one cup of coffee
How to create a bootable macOS Mojave 10.14 USB install drive:- Download the macOS Mojave files. You can download it from Mac App Store.
- Once you have your Mojave file all ready to go, close the installer that automatically pops up. You don’t want to be installing it just yet.
- Open a Finder window and head to Applications. Right-click on Install macOS 10.14 and select the Show Package Contents option.
- Open Contents > Resources. You’re going to need something from this sub-folder from here in a minute.
- Fire up Terminal either via Spotlight or from Applications > Utilities. Once open, type sudo followed by a space.
- Drag the createinstallmedia to that newly opened Terminal window.
- Now enter the following command, which will once again be followed by a space: –volume.
- Next up and back in Finder, select Go > Go To Folder. In here type /Volumes and click the Go button.
- Connect your USB drive and watch for it appearing in the Finder window.
- Drag the USB drive volume into the still open Terminal window.
- Press return, submitting the command that we just built via the magic of drag and drop.
- Type a y when prompted and hit return again.
- Go and make a coffee – this whole process can take around 30 minutes and will see the USB drive be erased before the installer is copied over.
After the flash drive is created - restart the Mac holding down the Option key, so you boot from the USB flash drive to begin installing the macOS Mojave.