You may need to reformat your new hard drive before installing macOS or OS X on it.

macOS could not be installed, how-to fixįormat your new hard drive for macOS or OS X.

How to create a macOS Catalina USB installer.Factory reset MacBook Air and other Macs with macOS.How to downgrade from macOS Mojave to macOS High Sierra.Or use the OS X installation disc that came with your machine - or buy a new one - to boot up and install OS X on your Mac’s hard drive.Download the relevant macOS or OS X installer from Apple, then use Terminal to create a USB installer you can boot up from.Install macOS or OS X from Internet Recovery Mode, which you can boot into by holding option+command+R while your Mac powers up.If you’re tech-savvy but don’t know where to start, use these Quick Tips to point you in the right direction for getting macOS or OS X on your drive: Simply follow the instructions below to install the latest compatible version of macOS or OS X on your new hard drive. So, it doesn’t matter if you want a clean slate on a second-hand MacBook or if you replaced the drive in your age-old machine, we’ve got you covered. In this article, we’ve given detailed instructions for each method. Fortunately, there are also several ways to do it, ranging from Internet recovery to installation discs. You can now quit Terminal and eject the volume.There are several reasons you might need to install a new copy of macOS or OS X on the hard drive in your Mac or MacBook. When Terminal says that it's done, the volume will have the same name as the installer you downloaded, such as Install macOS Monterey.After the volume is erased, you may see an alert that Terminal would like to access files on a removable volume.Terminal shows the progress as the volume is erased. When prompted, type Y to confirm that you want to erase the volume, then press Return.Terminal doesn't show any characters as you type. When prompted, type your administrator password.If the volume has a different name, replace MyVolume in the command with the name of your volume. Each command assumes that the installer is in your Applications folder, and MyVolume is the name of the USB flash drive or other volume you're using. Type or paste one of the commands below into Terminal, then press Return to enter the command.

Open Terminal, which is in the Utilities folder of your Applications folder.Plug in the USB flash drive or other volume that you're using for the bootable installer.

Mac os bootable drive