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How to Create macOS Big Sur Bootable USB

The following is a guide for creating macOS Big Sur Bootable USB. The installation has been covered in another section. You can use this USB for a clean install of macOS Big Sur on your compatible Mac.

Before you start with this guide, here's are few requirements
  • A working Internet connection.
  • A 16 GB or larger USB Flash Drive.
  • A complete backup of your system. We advise you to perform a complete backup of your system along with the existing installation. In case something goes wrong, you can restore it using the backup you created.
To start with the guide, you'll also need to have access to fully functional computer running macOS Mojave or later. This requirement is must as you need to access to Mac App Store in order to download a copy of macOS and create an installation USB Flash Drive later on.

Download macOS Big Sur
The very first step is to download macOS Big Sur. The copy of macOS is available for free download for anyone who has purchased a Mac with macOS High Sierra or greater. To download macOS Big Sur, follow the steps below

1. If you're using macOS Mojave or later, you can obtain macOS Big Sur via Software Update. Click on Apple menu  > System Preferences, then click on Software Update. Alternatively, you can click on System Preferences and then click on Software Update.

If you're having trouble with Software Update, you can obtain a copy of macOS Big Sur via App Store. To Get macOS Big Sur and click on GET button to continue downloading macOS Big Sur.

Creating a Bootable USB Flash Drive with Createinstallmedia
The next step is to create a bootable installation drive. Follow the steps below to create the installation media.

1. Insert your USB Flash Drive and open Disk Utility. The Disk Utility is located at /Applications/Utilities/Disk Utility
2. Select your USB Flash Drive in the left pane and click on Erase button, at top.
3. A pop-up will appear.
4. Under Name type USB

5. Under Format select Mac OS X Extended (Journaled)

6. Under Scheme select GUID Partition Map, and click on Erase.

7. When done, click on Done.

8. Launch terminal, located at /Applications/Utilities/Terminal.

9. Copy and paste the following sudo command in terminal.

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/USB

10. Enter your password

11. Press (Y) to confirm and then press enter key and it will start to erase the disk and will create macOS Bootable USB.

Once the process completes, close the terminal. The USB Flash Drive will be renamed as Install macOS Big Sur.

If you're looking for a clean installation guide, you can follow the guide below.
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