If you do not have a backup, then you end up losing all your data stored in the Mac drive. Backup helps to restore all the data back to Mac’s internal storage drive, containing the new macOS. While performing macOS upgrade or fresh installation, you must back up data to an external storage medium.

Keep the installer drive on a safe place so that you can use it as an external recovery drive when your Mac gets into trouble.ĭata Recovery on macOS: Why We Need It Here.

When Apple releases newer Mojave versions, re-download the new installer and recreate installer drive to keep it up to date.

Allow the computer to boot from the USB flash drive.

Alternatively, hold the option key and reboot the Mac then use the arrow key to select the USB flash drive as an installer.

For T2 security chip supported by 2018 MacBook Pros and iMac Pros, you need to “allow booting from external media” from Startup Security Utility.

Backup the entire drive before performing a clean install on your Mac machine.

Note: Erase the flash drive to HFS+ (Mac OS Extended (Journaled)) but not APFS. The Terminal creates the installer drive on the opted USB flash drive.

Type the administrator password when prompted.Warning: The command erases the flash drive so check there are no stored files backup the files, if they exist, before executing the sudo command. Open Terminal and enter the next command: sudo (drag and drop the installer from application folder to locate its path) –volume (drag and drop the USB flash drive from the Mac volumes to specify its path) –nointeraction –downloadassets.Connect the USB flash drive with at least 8 Gigabytes storage space to your Mac.Locate the installer from the Applications folder (copy it to the desktop if you desire).When the download completes, quit the installer, as it will launch itself automatically.Download macOS Mojave 10.14 from App Store.Data Recovery on macOS: Why We Need It Here.

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