How to downgrade from macOS Big Sur to Catalina?

Apple releases its new Mac update on November 2020, Big Sur. The latest version of macOS brought an all-new look and tons of features. Although it might be an exciting topic, for some to know about macOS Big Sur, however; it can be also quite the opposite.

If you have recently upgraded your macOS from Catalina to Big Sur, then you have noticed the changes. These changes can be painful for some people because now their favorite app doesn’t work anymore or has become buggy, or maybe they just need Big Sur to test an application, and now they are stuck. Reasons can be many, but all need an answer to “How to downgrade macOS from Big Sur to Catalina?”.

If you are looking for the same answer, don’t worry because, in this article, we will talk about all the ways you can use to downgrade your MacOS Big Sur.

Before Downgrading to Catalina

Before we start our process, it’s important to point out that if you have any personal or essential data on your Mac, it’s wise to make a backup first, since we will erase all the data from the hard drive and perform a clean installation. Although Mac has Apple’s Time Machine, still we don’t recommend relying on it, as it will also backup Big Sur too.

If you have already backed up your data on iCloud, you don’t have to worry about it. Else, grab an external hard disk or flash drive and store all your important files before you lose them forever.

Related: Install Windows 10 on macOS Big Sur using Boot Camp

How to Downgrade from Big Sur to Catalina

downgrade from big sur to catalina
downgrade from Big Sur to Catalina

There are many different methods to downgrade your macOS. Some of them are easier as compared to others. Navigate between the methods and select the one that looks the most suitable to you.

Related: How to Create macOS Big Sur ISO Image File?

1- Downgrade using Time Machine

Among all the methods, the easiest way is to use Time Machine to downgrade your Big Sur. If you have a backup of your system before you upgraded to Big Sur (which everyone must do), we can use that backup to downgrade our Mac from Big Sur to Catalina.

Note: Once again, before starting the process, make sure all your files that include photos, songs, and others are backed up and are totally safe. If you have stored them on iCloud, ensure that they are available on the iCloud. Once you are confident about your files’ safety, then we can start the process.

1: Connect your Time Machine to your Mac.

2: Restart your System.

3: While your system starts, hold down Command+R keys until the Apple logo appears.

4: A new screen will appear with many options, select Restore From Time Machine Backup and click on the Continue.

5: Click on the Continue in the next screen as well.

6: Now select your source for the restoration which basically is the Time Machine disk.

7: In the following screen, you will be asked to choose a specific backup from the list. Ensure that you have selected the backup that you have before upgrading your Mac to Big Sur.

8: Wait for the Mac to restore from backup, and you will have your old system back.

That is how you have your Catalina back, but if you don’t have any Time Machine backup, then follow the other methods.

Related: How to Fix macOS Big Sur (BiError Domain Error 3.)?

2- Downgrade by Reinstalling Catalina

If you don’t have any Time Machine backup, don’t worry; this method will downgrade your Mac without any Time Machine. Since we will completely erase the hard disk, make sure you already have backup your important data, though make sure not to backup it with Time Machine because it backups Big Sur too.

This method includes reinstalling Catalina, which means that you need external storage and make sure that your Mac can boot from external media.

You can enable boot from external media, if not already, by following these steps:

1: Boot your Mac into Recovery mode (hold Command+R until the Apple logo shows up).

2: In Utilities go to Startup Security Utility and enter your firmware password (note that your firmware password is different than to your admin or Apple ID)

3: In External Boot, check the box next to Allow booting from external media.

Now your Mac can boot from an external medium.

External bootable media

Next, you need external bootable media, which will be used to install Catalina, you can use any sort of media, but USB is the most common choice to make a bootable drive.

1: Open Apple Store and search for “Catalina,” and click on Get.

Related: Free Download macOS Catalina Virtual Disk Image

2: The system update will pop up a confirmation message. Confirm your download, and also, another message might pop up giving you a warning about download an older version of macOS; just ignore it.

3: Once the download is complete, keep it as it is; don’t install it.

4: Ensure you have an external drive with 12 GB of free space and plug it in.

5: Format your drive if it’s not already. You can skip the following step if your drive is formatted.

if you have not formatted your USB then go to Utility and then Disk Utility. Then locate your external drive and click on Erase next to it. Select APFS or macOS Extended format and Erase.

Installing Catalina on an External drive

Now is the time to install macOS Catalina. Here is what you need to do:

1: Open Finder and then Application.

2: From Utilities open Terminal.

3: Enter the following command:

sudo /Applications/Install\ macOS\ --volume /Volumes/MyVolume

Note: While typing code, in the end, replace “MyVolume” with the name of your external drive.

4: Enter your command, type the admin password if asked, and press Y to confirm your action.

5: Once the Terminal said Done, you can unplug your drive safely.

Related: Free Download macOS Big Sur ISO for Virtual Box

3- Replacing your Big Sur with Catalina

Now that everything is set, we can start our primary process.

1: Plugin your bootable drive, open System Preference by clicking on the Apple icon in the corner.

2: Open startup disk, select your bootable drive as startup disk and click on Restart.

3: Your Mac will restart in Recovery mode; ensure that you have an Internet connection during the installation process for the firmware update.

4: In the Utility window, select install macOS and click on Continue.

Now your Mac will start installing Catalina and will restart once done. You can now use your macOS Catalina, in case; if you’re facing any slow down in your system’s performance, try getting iStat Menus. It’s a 7-day trial app that will help you to detect the cause of the slowing down.

Related: Free Download macOS Big Sur ISO Image

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