Put the macOS High Sierra installer on an external USB thumb drive or hard drive and use it to install the operating system on a Mac. By Roman Loyola Senior Editor Macworld Sep 29, 2017 11:23 am PDT.
It does not matter whether you use macOS or Windows 10. It’s just a matter of time until your device will refuse to start, which could happen for many reasons, including (and not limited to) file corruption, hardware failure, and buggy update. If the unexpected happens with an Apple computer, you can use a macOS bootable USB with the installation media to repair it.
This is one of the main reasons you should consider making a macOS bootable USB when your device is working properly. However, if none of your devices (MacBook, MacBook Air, MacBook Pro, iMac, Mac Pro, or Mac Mini) aren’t working when you need them the most, then you can use a PC to rescue your Apple device. You can use a Windows 10, Windows 8.1, or Windows 7 device to quickly create a USB bootable installation media to reinstall macOS Catalina or Big Sur on your Mac.
In this guide, you’ll learn the steps to create a macOS Catalina bootable USB installation on Windows 10, which you can use to reinstall or upgrade the Apple OS.
Before proceeding, you’ll need the following:
To create a bootable USB drive with macOS, use these steps:
Download and install TransMac on the Windows 10 device.
Connect the USB flash drive. (If you have any data on the flash drive, remember to make a backup, as everything on it will be erased.)
Right-click the TransMac app and select the Run as administrator option.
Click the Run button. (If you’re using the trial version, wait 15 seconds.)
Right-click the USB flash drive, select the Format Disk for Mac option from the left navigation pane.
Click the Yes button to format the drive on the warning message.
Confirm a name for the drive. For example, “macOS bootable USB.”
Click the OK button.
Click the Yes button.
Click the OK button.
Right-click the USB flash drive and select the Restore with Disk Image option from the left navigation pane.
Click the Yes button to confirm the erase of the USB flash drive data.
Click the browse button on the right.
Select the .dmg file with the macOS installation files.
Click the Open button.
Click the OK button.
Click the Yes button.
Once you complete the steps, you can now insert the USB flash drive on your Mac computer to install, reinstall, or upgrade the operating system to the latest macOS version, which can be Sierra, Catalina, Big Sur, or higher.
If the USB flash drive is not working with TransMac, it could still be a partition problem. In this case, you may need to redo the entire process again. However, this time you should use the following steps to use the Diskpart command-line utility on Windows 10 to create the appropriate GPT partition, and then follow the above instructions.
To create a GPT partition on a removable drive, use these steps:
Open Start.
Search for Command Prompt, right-click the top result, and select the Run as an administrator option.
Type the diskpart
command and press Enter.
Enter the list disk
command to view all drives connected to your computer and press Enter.
Type the select disk
command followed the number assigned for the USB flash drive (for example, select disk 4
), and press Enter.
Enter the clean
command and press Enter.
Type the convert GPT
command and press Enter.
Enter the create partition primary
command and press Enter to complete the process.
Once you formatted the USB flash drive with a GPT partition, you can use the instructions mentioned above to use TransMac to create a bootable media, but this time skip steps No. 5 through 10 and continue on step 11.
After the process completes, which can take up to an hour, connect the USB flash drive and power on your Mac holding down the Option key, select the USB drive to begin installing macOS.
If you have problems creating the bootable media, you can get a USB flash drive that comes with macOS Sierra, El Capitan, Catalina, etc., on it with the link mentioned below. (I haven’t tried it personally, but it’s worth the try if nothing works.)