Forum Discussion
MichaelMiller
Mar 03, 2026Bronze Contributor
macOS High Sierra dmg download for making bootable usb insttaller
My old Macbook Air needs a clean reinstall as the disk was erased and no os on it. Currently, macOS High Sierra is the best option but I am unable to download the dmg file from Apple website. It only...
Olddies
Mar 03, 2026Silver Contributor
This method allows you to create a bootable macOS High Sierra installer USB after you have completed the macos high sierra download and have the installer app in your Applications folder. It works on any Mac running macOS.
What You Need
- USB drive
- macOS High Sierra installer app
- A working Mac
1.Insert the USB drive into your Mac
- Open Disk Utility.
- Select the USB drive from the left-hand sidebar.
- Click the Erase tab.
- Set the format to Mac OS Extended and the partition scheme to GUID Partition Table. Name it MyVolume
- Click Erase to format the drive.
2.Run Terminal commands
- Open Terminal
- Copy and paste the following command, replacing ‘MyVolume’ with your USB drive's name if different:
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
- Enter your administrator password when prompted
- Type Y and press Enter to confirm
3.Wait for completion
- The process will take 10–20 minutes, showing progress with Erasing Disk and Copying messages.
- Do not interrupt the process. When finished, you will see "Install media now available at /Volumes/Install macOS High Sierra.
This method provides a reliable approach to creating a bootable installer after downloading macOS High Sierra. Whilst it requires a certain level of familiarity with Terminal operations, it remains a trustworthy solution for generating installation media.