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Creating a Restore Disk for M1 and Intel Macs | Downgrade macOS Big Sur to Catalina!

9:22 video

You updated macOS to fix an annoying bug and now have worse ones. I can’t fix that right now, but I can help you prepare for the next update by showing how to create a bootable flash drive so you can downgrade if needed. Over the last couple of years Macs have had bugs, some minor (Bluetooth disconnects) and some awful (not booting after connecting certain USB docks, external displays not turning on or coming up in a weird resolution). Apple has made it harder to download previous macOS versions after new ones release, so this shows how to create a bootable drive of your current version, and at the end how to revert to a previous major release if your computer shipped with it (for example, from Big Sur back to Catalina).

What you need

A flash drive of at least 16 GB (the whole drive will be erased). I like the SanDisk Ultra Dual Drive, which has USB-A and USB-C connectors and is pretty speedy (a 32 GB version for about $10 and a 64 GB version for about $15, linked in the description).

Creating the install drive

  1. Download the current macOS from the Mac App Store (at the time, Big Sur 11.2.3). It may take a while. When it finishes, the installer opens automatically: quit it, and you’ll see Install macOS Big Sur in the Applications folder.
  2. Open Terminal and paste the createinstallmedia command from the Apple support article linked in the description (use the Big Sur command for Big Sur). It uses elevated permissions and copies the files to your drive. Change the volume name in the command to your USB drive’s actual name (mine was “flashdrive”). Allow Terminal permissions if asked.
  3. Press Enter, type your admin password (and retype it if you mistype), and type Y to agree to wipe the drive. It formats the drive, copies the files and makes it bootable, which takes at least a few minutes depending on the drive’s speed.

For my own sanity, I create a folder in the root named for the macOS version. I plan to make a flash drive for each macOS version and keep a few around: wrap each in tape and write the version on it. As a bonus, you can copy the Install macOS Big Sur app to another drive or backup.

Downgrading or reinstalling on an M1 Mac

Downgrading means erasing your Mac’s disk, losing all data: afterward, restore files and apps from a Time Machine or other backup.

  1. Boot into recovery by holding the power button from shutdown until you see “Loading startup options,” then click Options and Continue, and enter your account password.
  2. Open Disk Utility, choose View > Show All Devices, select the APFS container above Macintosh HD and click Erase. Follow the prompts and reboot when told.
  3. The Mac must activate like an iOS device, so connect to Wi-Fi (and, if Find My was on, enter your Apple ID and password).
  4. If you continue with the install now, it installs from the internet. Instead, shut down, insert the USB drive and boot into startup options again, then choose your install disk.
  5. I found you need to erase the disk again: quit the installer, open Disk Utility, show all devices, select the APFS container and erase again. Then quit Disk Utility and start the installation: select your disk and follow the prompts.

In 20 to 60 minutes, you can set the Mac up as if it were new, running the macOS you installed.

Differences on Intel Macs

  • Boot into the flash drive by holding the Option key and selecting it.
  • With a T2 chip, change the security settings first: enter recovery by holding Command-R at boot, enter your admin password, choose Utilities > Startup Security Utility, enter your password again and check Allow booting from external or removable media. Then reboot into the install media, wipe the disk and install.

Reverting to the shipped macOS (Intel only)

This works only if your Mac is Intel-based and came with the previous major release, such as a 2019 or 2020 iMac that shipped with Catalina and was upgraded to Big Sur. Boot into recovery holding Shift-Option-Command-R, connect to Wi-Fi or Ethernet, and it boots into the major macOS release your computer shipped with. Follow the prompts, erase the disk, and you’ll have a fresh install.

Restoring from backup or reinstalling apps can be a pain, but if a bug is wrecking your workflow, downgrading may be the only option. Make sure you have a good backup first: see my video on backing up Macs with Synology.

In this video

  • 0:00 intro
  • 1:19 creating an install disk
  • 4:12 M1 recovery, disk wipe, and install
  • 6:47 Intel Mac and Macs with T2
  • 7:59 downgrade from Big Sur to Catalina

Some links in this post are affiliate links, which means that if you click on one of the product links, I may receive a small commission. See my ethics statement.

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