Follow the on-screen instructions to reinstall macOS Catalina. Downgrade macOS Big Sur with a macOS Catalina bootable installer. If you have some trouble with the above two ways, you can try to downgrade macOS Big Sur via creating a macOS Catalina bootable installer. Download the Big Sur install files. If you want to reinstall Big Sur and are already running Big Sur the best way to access the installer for Catalina is via the Mac App Store. Here's a link to. Revert big sur to Catalina failed. Good morning folks. I installed the public beta for Big Sur and tried to revert to Catalina. I’ve done this in previous years, no big deal. I go to reinstall Catalina through command option r and hit the prompt to reinstall Catalina, everything seems to be going fine. Type a name for the volume in the Name field, click the Format pop-up menu and choose APFS, then click Erase Volume Group. When the erase process is complete, click Done, then choose Disk Utility Quit Disk Utility. In the Recovery app window, select “Reinstall macOS Big Sur,” click Continue, then follow the onscreen instructions.

1. How Do I Reinstall Catalina From Big Sur
2. How Do I Reinstall Os X Catalina From Big Sur
3. How To Update Macos Big Sur

Reinstalling the OS of your Mac is sometimes required as a last resort option when troubleshooting a certain software problem. If none of the other fixing methods have worked out so far, this final fixing method should be enough to bring things back to normal and restore your Mac to its regular state.

However, before you continue with the macOS reinstallation, we advise you to make sure that you have indeed exhausted all other options and made sure that this really is the only thing that you haven’t tried so far. If that is your case and you are sure you wish to continue, here is a guide that can help you with the reinstallation process.

Accessing macOS Big Sur Recovery

MacOS Recovery is a special mode that gives you access to different system repair tools that can help you deal with different issues that your Mac has. In the macOS Recovery Mode, you can use the Time Machine backup tool, get online help for your problem, erase the hard drive of your Mac, reinstall your macOS, and more.

Entering Recovery Mode is a bit different depending on whether your Mac has an Apple Silicon or an Intel processor. To find out the type of processor that your Mac has, click on the Apple Menu, select About this Mac, and look at the information in the window that opens. If you see an entry labeled Chip with the model of the chip written after it, this means that your Mac is with an Apple Silicon processor. If instead of that there is a “Processor” entry followed by the specific processor model, it means that your Mac is equipped with an Intel processor. Depending on which one of the these two your Mac has, do either of the following:

• Macs with Apple Silicon processors: With the computer turned off, press and hold down the Power Button, wait for the Startup Options screen to get displayed on your screen, and then release the button. Now select the Options icon and click on Continue.

• Macs with Intel processors: Make sure that your Mac is connected to the Internet and turn it off. Then start the computer and immediately after that hold down the Command ⌘ + R keys from the keyboard. Keep holding them until the Apple logo (or another image) gets displayed on the screen.

How Do I Reinstall Catalina From Big Sur

If your Mac requires you to log in to any of your Mac accounts, select an account you know the password for and that has Admin privileges.

Reinstalling macOS Big Sur from Recovery Mode

Now that you have entered Recovery Mode on your Mac, it is time to reinstall the OS of the computer.

1. From the Utilities screen of the macOS Recovery, select the Reinstall option and click on Continue.
2. Follow the on-screen instructions and steps – they will guide you through the whole process.
3. Be sure to adhere to the following tips while in the process of reinstalling macOS.
   • Do not put your Mac to sleep or close its lid while the reinstallation process is underway. While macOS is being reinstalled, your Mac may restart several times and the screen may go black and stay that way for several minutes – even if this happens, stay patient and wait for the process to complete. Until macOS gets reinstalled, do not close, put to sleep, or turn off your MacBook!
   • If you are asked to unlock the disk of your Mac, do so by filling in the password that you use to log in to your main Mac account.
   • If the macOS installer cannot find your disks or it tells you that the installation cannot be completed on the specified disk, you may first need to erase that disk and try again.
   • If you are given the choice between installing Macintosh HD or Macintosh HD Data, pick the first option.

Once the installation of macOS is complete, you will be asked to set up the preferences of the computer. Complete the set up according to your personal preferences and you will be good to go.

If you have reinstalled the OS because you intend to sell or give away your Mac and want to allow its new owner to set it up themselves, press Command-Q to close the Setup Assistant and leave the setting-up process to the future owner of the computer. After that, click on the Shut Down button to turn off the Mac.

Additional options and tips for installing/reinstalling macOS

The default setting of macOS Recovery is that it will install the latest version of the operating system that was previously installed on the computer. If you want, you can get it to install a different version of the OS by using one of the following options:

• On a Mac with an Intel processing unit, you can press down and hold the Option + Command + R keyboard combination (instead of the Command ⌘ + R combination) as soon as you turn on the computer. This will cause macOS Recovery to install the latest stable macOS version that is compatible with the machine. There are two exceptions here:
  • If macOS Sierra 10.12.4 or another later version of macOS has never before been installed on the computer, the macOS version that will get installed will be the one that originally came with the machine, or another macOS version that is closest to the original one.
  • If the computer is equipped with the Apple T2 Security Chip and a macOS update has never before been installed on the machine, macOS Recovery will install the latest version of the OS that was installed on the computer.
• If your Mac previously had the macOS Sierra 10.12.4 version of the OS or a later version, you can also use the Shift + Option + Command + R combination once you start the computer (press and hold the mentioned buttons) instead of the two previous combinations to make macOS Recovery install the OS version that was originally on your Mac when you bought it or the closest other OS version that is still available.
• To install a different macOS version that macOS Recovery doesn’t allow you to install, you can instead go to the App Store and install the desired OS version from there.
• Another way to reinstall your macOS is to create a bootable USB drive and install the desired OS version from it.
• If the logic board of your Mac has just been replaced after your machine has been repaired by a technician, it is likely that macOS Recovery will only offer you to install the latest OS version that is compatible with the computer.
• If the entire disk of your Mac has just been erased (instead of only the startup volume), macOS Recovery will probably only allow you to install the version of the OS that came with the computer when you first bought it (or the closest other available macOS version).

I’ll admit it: I’ve gotten a little used to working at smaller companies, where there’s no monitoring of company computers, and it’s the Wild West as far as what you can install on them.

That’s no longer the case for me. I now work at Auth0, a company with a headcount that’s quickly approaching 800, with unicorn status and Series F funding, and it’s in the security industry. Naturally, there’s a full-fledged security team that monitors company-issued computers.

In my excitement to take the new version of macOS — Big Sur — out for a spin, I’d forgotten that the Security team hasn’t yet approved it for use. They very quickly (and I should add, nicely) contacted me and let me know that I needed to reinstall macOS Catalina as soon as possible.

There are other reasons why you might need to go back to Catalina after installing Big Sur:

• It’s still very new, and very new versions of operating systems always have some set of issues, whose effects can run the gamut from mildly annoying to catastrophic. If you can’t afford to lose time dealing with these issues, you should wait for the updates.
• There are reports that the current version can “brick” MacBook Pros from the 2013 / 2014 era. This isn’t a problem if you’re keeping your old 2013 / 2014 machine around as a backup, but more serious if you’re still using it as your main computer (and yes, a 2013 / 2014 Mac is still a perfectly good machine, even for development work).
• If you’re a DJ or music producer, Big Sur currently has compatibility problems with some of the hardware and software. If you want to keep DJing, producing, or mixing on your Mac, stay on Catalina for a little bit.

For the benefit of any who need to downgrade, here’s a step-by-step guide to reinstalling Catalina after you’ve installed Big Sur. You’ll need a USB key and the better part of an afternoon.

Step 1: The preliminaries

1a: Start downloading the Catalina installer from the App store

The first thing you’ll need is the macOS Catalina installer.

It’ll take up around 9 gigabytes of space on your hard drive, and the App Store will put in your Applications folder.

Once it’s completely downloaded from the App Store, the installer will start automatically. When this happens, close the installer. You’ll make use of it later.

The installer will take some time to download. Apple’s servers will be busier than usual, as many users are downloading Big Sur and other upgrades.

1b: Back up your files!

In the process of reinstalling Catalina, you’ll need to completely erase your Mac’s hard drive. If you have any files that you can’t live without, this is the time to back them up.

I didn’t have to worry about this, since:

• All my work product is either code (which lives on GitHub) or content (which lives on GitHub or Google Docs), and
• I’ve been at Auth0 less than a month, and between onboarding and offsites, there just hasn’t been that much of a chance for me to accumulate that many files on my hard drive!

1c: Get a nice fast USB key that stores at least 16 GB

The process will involve booting your Mac from a USB key containing the macOS Catalina installer, so you’ll need a key with enough space. An 8 GB USB key won’t be big enough. Because digital storage is all about powers of 2, the next size up will be 16 GB.

I strongly recommend that you use a USB 3 key, especially one with read speeds of 300 megabits/second or better, such as the Samsung Fit Plus. Doing so will greatly speed up the process. Don’t use a USB key that you got as conference swag — it may have the space, but more often than not, they tend to be slow, because they’re cheap.

If the USB key contains files that you want to keep, back them up. You’re going to erase the key in the next step.

Step 2: Make a bootable USB key containing the macOS Catalina installer

2a: Format the USB key

Plug the USB key into your Mac, then launch Disk Utility.

Select the USB key in Disk Utility’s left column, then click the Erase button:

You’ll be presented with this dialog box:

Enter MyVolume into the Name field, and for Format, select Mac OS Extended (Journaled). Click the Erase button. This will format the USB key with the volume name of MyVolume.

2b: Install the macOS Catalina installer onto the USB key

In Step 1a, you downloaded the macOS Catalina installer and closed it after it started automatically. In this step, you’ll transfer it to your freshly-formatted USB key.

Open a terminal window and paste the following command into it:

(The command above assumes that you gave the USB key the volume name MyVolume.)

Once you’ve provided sudo with your password, you’ll be asked if you want to erase the USB key. Entering Y in response will start the process of making the USB key a bootable drive and copying the macOS Catalina installer onto it:

The Erasing disk process will be relatively quick, but the Copying to disk process may take a while. This is where using a nice, fast USB 3 key will pay off.

Be patient and let it get to 100%, and wait for the Install media now available message to appear and the command line prompt to return.

2c: If your Mac is from 2018 or later, set it up to boot from external media

Check the year of your Mac’s manufacture by selecting About This Mac under the Apple menu:

• If your Mac year is 2017 or earlier, you don’t need to follow the rest of this step. Proceed to Step 3.
• If your Mac’s year is 2018 or later, you’ll need to change its security settings to allow it to boot from an external drive.

Here’s how you change the security settings:

1. Restart your Mac and hold down the ⌘ and R keys when you see the Apple logo. This puts the computer into recovery mode, which provides many setup options.
2. In the menu bar, select Utilities, and then select Startup Security Utility from the list that appears.
3. The Startup Security Utility window will appear:
   1. Under the Secure Boot section, select Medium Security. This will allow you to install Catalina without having to connect to a network.
   2. Under the External Boot section, select Allow booting from external media. This will allow you to install Catalina from a USB key or disk drive.

Step 3: Install macOS Catalina

Restart your Mac, and hold down the Option key while it restarts. Your Mac will present you with a choice of startup disks.

Choose the USB key. Your Mac will boot up and you’ll be presented with the macOS Catalina installer screen:

Go ahead and install Catalina.

How Do I Reinstall Os X Catalina From Big Sur

Once Catalina is installed, you can proceed reinstalling your other software.

How To Update Macos Big Sur

Once that’s complete:

• If your Mac’s year is 2017 or earlier, you’re done installing Catalina. You can now go about reinstalling your software and restoring your backed up files.
• If your Mac’s year is 2018 or later, you’ll need to restore its original security settings. The process is described in Step 4, below.

Step 4: If your Mac is from 2018 or later, restore the original security settings

If your Mac is from 2018 or later, follow these steps to restore the original security settings once Catalina has been installed:

1. Restart your Mac and hold down the ⌘ and R keys when you see the Apple logo. This puts the computer into recovery mode, which provides many setup options.
2. In the menu bar, select Utilities, and then select Startup Security Utility from the list that appears.
3. The Startup Security Utility window will appear:
   1. Under the Secure Boot section, select Full Security.
   2. Under the External Boot section, select Disallow booting from external media.