NOTE: If your Mac came with macOS Catalina, you can restart your Mac while holding down Shift-Option-Command-R to enter Internet Recovery Mode and install the operating system that came with your Mac.

If Scheme is available, select GUID Partition Map.Īfter the process is complete, quit Disk Utility from the drop-down menu in the upper left corner of the screen to go back to the OS X Utilities selector.Īfter you have erased your hard drive, you will want to reinstall Catalina.

If your Mac is using APFS, select APFS from the format list.

If your Mac is using HFS+, select Mac OS Extended (Journaled) from the format list.

After the drive is erased, it will be changed to this new name.

Enter a new name for the hard drive, like Macintosh HD.

Click on Disk Utility in the OS X Utilities selector.Ĭlick on the Erase tab at the top of the window.

This will put your computer into Recovery Mode.

Hold down Command+R, and keep holding the keys until your computer reboots.

Click on the Apple icon in the upper left corner of the screen.

Connect your Mac to the internet via Wi-Fi or Ethernet.

Remember, back up your Mac before performing this step. You'll need to erase your hard drive before re-installing Catalina. If you don't feel comfortable making changes to your Mac with Terminal, you can create a bootable disk using the DiskMaker X program. Note: Making a bootable installer requires the use of Terminal.

How to make a bootable macOS Catalina installer drive in case you want to downgrade from macOS Big Sur.

You'll need a copy of macOS Catalina on an external hard drive for the easiest, fastest way to install the downgrade.įollow the steps linked below to make a bootable installer drive for macOS Catalina

Step 2: Create a bootable drive of macOS Catalinaīefore you downgrade your Mac and erase Big Sur from your computer, download macOS Catalina from the Mac App Store. If you don't save these important files somewhere off of your computer you will lose them. Use an external hard drive or a cloud-based program like DropBox, OneDrive, or iCloud. Erasing a hard drive means erasing everything. You also won't just revert back to the previous macOS with all of the files and folders exactly where you left them. That means any files, programs, or documents you've been working on will also be erased if you don't back them up first. This process to downgrade your Mac will erase macOS Big Sur from your hard drive entirely. Tick the box to Allow booting from external media.

This will put your Mac into Recovery Mode. Hold down Command+R right when you see the Apple Logo.Make sure you know the correct password to access the Startup Security Utility before you begin. This is different from your administrative password and your Apple ID. Note: You'll need the firmware password you used to enable the Startup Security Utility.

Downgrade mac os