Install Catalina From Big Sur

Modifying Aperture and iPhoto to run on macOS Big Sur or macOS Catalina should only take about 2 minutes. If you chose to install iTunes, this process takes longer. Reinstall macOS Catalina on Your Mac. Restore Time Machine Backup (Optional) Step 1. Back up your Mac (Very Important) If you want to downgrade from Big Sur to Catalina without losing data, it is important to save and backup your data on the macOS Big Sur, so you do not lose any important files. Download macOS Big Sur. If you're using macOS Mojave or later, get macOS Big Sur via Software Update: Choose Apple menu System Preferences, then click Software Update. Or use this link to open the macOS Big Sur page on the App Store: Get macOS Big Sur. Then click the Get button or iCloud download icon. But Migration Assistant has its limits: in Catalina and Big Sur, you must migrate from a backup made from or a computer running Mac OS X 10.11 El Capitan or later. Attempts to copy from older. With my system now working on OC 0.6.3, I created an OC Big Sur install USB, kicked off the install/upgrade, did the 3 or 4 reboots and that’s it. Successful Catalina/OC to Big Sur upgrade. So far everything but on-board Audio works, but that was also the case in Catalina.

Summary: This page is about how to reinstall macOS in macOS Recovery mode. Based on if you want to keep the original data on the startup disk, you can either choose to clean reinstall macOS or to reinstall macOS without data loss.

Reinstalling macOS gives your Mac a fresh start especially when you are frequently bothered by some issues, such as Mac not turning on, Mac hanging on the beach ball, apps frozen on your Mac, slow performance, or pink screen on Mac. Most of the time, such issue results from some system-level problems, while reinstalling macOS can easily save your life.

• How to reinstall macOS on an M1 Mac?

How to reinstall macOS from macOS Recovery mode?

When you need to reinstall macOS on your Mac, macOS Recovery mode makes this process easy and quick. By the way, if you want to learn more about macOS Recovery mode, you can watch this video.

To reinstall macOS in macOS Recovery mode:

Step 1: Make sure your Mac is connected to a stable Internet within all the following steps.

Step 2: Identify it's an Intel or M1 Mac, and immediately do one of the followings.

Press and hold Command + Option + R.This allows you to reinstall the latest version of macOS that is compatible with your Mac computer from the internet.
Press and hold Shift + Command + Option + R. This option allows you to reinstall the macOS that came with your Mac, or the closest version still available.
Press and hold Command + R. This allows you to reinstall the version of macOS stored on your built-in recovery disk, including any updates that you installed.

• How to Boot into & Use M1 Mac Recovery Mode

Step 3: Release these keys when you see an Apple logo, spinning globe, or the Utilities window.

Step 4: Enter the requested password if you are prompted to enter a firmware password or the administrator's login password.

• Recover/reset your forgotten Mac password

• Mac won't accept correct password, what to do?

Step 5: Decide if you want to clean install the system, or just reinstall macOS without losing your original data.

If you want to factory reset the Mac for selling or giveaway, or the startup disk becomes corrupted, you might want to erase the startup disk before reinstallation. This guarantees a fresh and clean installation as it wipes all your personal data on the disk.

• How to factory reset your Mac?

• How to reset your M1 Mac to factory settings?

If you only want to reinstall macOS because the original operating system is not working as you expect, you might want to keep your personal data intact. In case files are deleted or lost by accident during macOS reinstallation, you should have a backup of your data or getting files off first.

• How to get files off a MacBook that won't turn on?

Step 6: Either after erasing the startup disk or getting files off the Mac, you can then go back to macOS Utilities and choose Reinstall macOS. Check this post to find all macOS versions and know which one you are going to reinstall.

Step 7: Follow the on-screen instructions and choose a disk to reinstall the OS.

Install Catalina From Big Sur Torrent

If the internal startup disk is not showing up, or the installer says that it can't install macOS on your computer or volume, you might need to back up files and then erase your disk.
If the installer asks you to choose Macintosh HD or Macintosh HD - Data when installing macOS Catalina, choose Macintosh HD.

Other ways to install macOS

Apart from reinstalling macOS from macOS Recovery mode, you have other options according to your situations.

Get released macOS versions or updates by App Store or Software Update preferences.
Get macOS beta (such as macOS Monterey that might be buggy now) through Apple’s developer website.

Whatever your situation of reinstalling macOS is, you should always retrieve your data from the Mac before any further movement. After all, you can't tell if you want it back or not in the future.

If you have installed Big Sur, Catalina, Mojave or earlier versions, you may have to reinstall macOS for following reasons:

Reinstall When There is New macOS Version Available

Apple keeps working constantly to fix bugs, make performance tweaks, add new features or enhance coding. Therefore, doubtless, there will be new versions of macOS available to upgrade and reinstall.

Install Macos Catalina From Big Sur

Your Mac is Running Slow

As we all know, for no specific reason, system reinstallation can magically solve a slow Mac in most cases.

Your System Keeps Crashing or Works Improperly

When you continuously see error messages appear on your mac, or your programs randomly crash/freeze for no reason, like FaceTime won't work, Contacts or Calendar shows a delay or mess, blue teeth or WiFi won't connect…Then, you have a good reason to reinstall macOS.

You are Going to Sell the Mac

In the case that you want to sell your mac, besides erasing all your personal data and traces on the mac, you will need to reinstall macOS as well.

It is not complicate to reinstall macOS Big Sur or Catalina, but if you want to reinstall macOS without losing data, there are 3 steps you must follow.

Recover Files after macOS Reinstall

Recover data lost due to macOS reinstallation, upgrade, downgrade
Recover data lost due to accident deletion, formatting, etc.
Restore data from both internal and external storage device
Recover videos, audios, images, documents, and other 200+ files
5 recovery modes to find files back easily
High recovery rate
Support Big Sur, Catalina, Mojave and earlier

Free Download

3 Steps to Reinstall macOS Big Sur or Catalina without Losing Data

We all save tons of data on our Mac, so when we decide to reinstall macOS Big Sur/Catalina, the top concern always goes to “will I lost everything if I reinstall macOS”. In fact, reinstallation of macOS doesn’t necessarily cause lost data, it just create a new copy, your existing files and data saved in programs won't be altered or deleted. But just in case of bad luck, we need to do some work on BACKUP, this is crucial for macOS reinstallation without losing data.

Step 1. Prepare Your Mac for Reinstallation.

Make enough room for Big Sur or Catalina reinstallation, at least 36GB, so the reinstallation process won't pause or stopped for insufficient space.
Also, quit all apps or programs under work, so your Mac is fully geared to reinstall.
Check drive conditions. Open Disk Utility and perform the Frist Aid on your hard drive where to reinstall the macOS to make sure your drive is in good condition for reinstallation.

Step 2. Backup All Your Files for macOS Install (Crucial)

Backup is an indispensable step involved in the macOS reinstallation, here are several options to backup your data.

Option One: Using Time Machine

Go to Finder>Application, launch Time Machine and choose “Set Up Time Machine”.
Click “Select Backup Disk” to choose an external hard drive to back up the files.
Then Check the box before “Back Up Automatically”. Also, you can adjust the backup setting in menu “Options”.

How To Downgrade Big Sur To Catalina

If this is the first time you use Time Machine to backup, wait patiently for Time Machine to complete the backup, it will prompt the notification once finishes.

Option Two: Using Hard Drive

Connect your hard drive to Mac.
Open Finder to check if your hard drive is present under “Devices”.
Create a new folder, copy and paste or directly move the items you want to save from Mac to this folder.
Finally, eject your hard drive.

Option Three: Using iCloud Service (Backup Desk and Documents Folders)

Go to Finder>System Preference, click on “iCloud” to bring up its main interface.
Click the “Options” button for “iCloud”, and check the box before “Desktop and Documents Folders”, then click on “Done”.

Most of our mac users prefer to backup all files but apps. So, to save you from troubles of lost data due to macOS reinstallation, you are recommended to keep records of what apps you have installed, the account and password, also, you can take screenshots of the settings.

Step 3. Reinstall macOS Big Sur or Catalina without Losing Data.

Option #1: Reinstall macOS without Losing Data From Internet Recovery

Click the Apple icon>Restart.
Hold down the key combination: Command+R, you will see the Apple logo.
Then choose “Reinstall macOS Big Sur” from utilities window and click “Continue”.
Select your hard drive, click “Install” and wait for end of reinstallation.

Option #2 Reinstall macOS without Losing Data From USB

Download the macOS Big Sur install from Mac App Store onto your Mac;
Then connect the USB flash drive to your Mac;
Open Disk Utility program on your Mac, choose the USB flash drive and click Erase to have a clean drive for the reinstallation;
Open Terminal, copy and paste sudo /Applications/Install macOS Big Sur.app/Contents/Resources/createinstallmedia;
Then add the volume of usb flash drive: --volume /Volumes/MyVolume, replace MyVolume with your usb flash drive name, mine is Untitled;
Press Enter, input password and wait for the process to finish;
Quit Terminal, restart your Mac, hold Command+R when starting Mac until you see the apple logo;
Login into your Mac with password, go to the menu bar>Utilities>Startup Security Utility, enter password again;
Choose Medium Security under Secure Boot and allow booting from external media;
Restart your Mac, in the same time, hold the Option key;
Choose Install macOS Big Sur, click Next and input password, choose Install macOS, continue to finish mac reinstallation from usb.

Mac Won't Turn on after Update to macOS Big Sur?

Here are 10 solutions to fix 'Mac won't turn on after update to macOS Big Sur, Catalina or other versions'.

What if You Lost Data After macOS Big Sur Reinstallation?

Can I Install Catalina From Big Sur

However, losing data after reinstallation still happens. It may result from a interrupted installation (power-off/poor internet connection), corrupt setup, insufficient space or improper actions. Then, what to do if you lost data after reinstallation? Here are 2 methods.

Method 1: Use Cisdem Data Recovery to Recover Data

In the case you didn’t do backup before reinstallation, you will need a dedication data recovery program to find the lost data for you.

Here we recommend Cisdem Data Recovery, a powerful mac program allowing users to recover lost/deleted/corrupted/formatted files from a wide range of external or internal storage devices, no matter the file is lost due to human errors, power-off, reinstallation, upgrade, virus attack or disk crash.

Main Features of Cisdem Data Recovery

Recover files lost due to OS reinstallation, upgrade, downgrade;
Recover deleted, formatted and lost files;
Restore files from internal and external hard drive, USB, SD Card, flash drive, etc.;
Restore videos, audios, images, documents, archives, 200+ types;
5 recovery modes: Basic, External Drive, Formatted Drive, Trash, Advanced;
Preview files before recovery;
Fast scanning and recovery;

Steps to Recover Lost Data after MacOS Reinstallation

Download and install Cisdem Data Recovery on Mac.
Free Download
Choose a Recovery Mode according to your need.
If you want an efficient recovery, choose “Basic Data Recovery”, if you want to recover files with a higher success rate, try “Advanced Data Recovery”.
Select the hard drive where you originally stored the files on mac. Then click “Scan”.
Check and preview files found by Cisdem Data Recovery.
Select files to recover.
Check the box before files that you want to recover, then click “Recover” to find back the lost data caused by reinstallation.

Install Catalina Next To Big Sur

Method 2: Use Time Machine to Recover Data with Backup

Install Catalina From Big Sur Full

If you have backed up your files on mac, you can use Time Machine to restore the lost data.

Step1. Go to Finder>Applications>Time Machine, launch it and choose “Enter Time Machine”.
Step2. In the popped-up window, use the arrows and timeline to browse the local snapshots and backups.
Step3. Find the deleted files, then click “Restore” to recover the lost data caused by reinstallation.

Conclusion

The key to reinstall mac OS Big Sur, Catalina or Mojave without losing data is the backup, since no one can guarantee all data will be perfectly maintained after macOS reinstallation. However, if we unfortunately lost files after macOS reinstallation, Time Machine or Cisdem Data Recovery is helpful to recover them back.

So, do you have any other tips to reinstall macOS without losing data? Please share with more of our mac users.