macOS Big Sur is the operating system for Mac computers since its release in 2020 by Apple Inc. It succeeds macOS Catalina with significant visual changes and new features. Users may want to reinstall macOS Big Sur for various reasons like fixing system problems, cleaning up old files, or preparing to sell their Mac.
Reinstalling the operating system can help resolve issues caused by outdated software and other problems that accumulate over time. It essentially provides a fresh start by overwriting existing OS files with a clean, new copy. However, reinstalling will not automatically delete personal data like photos, documents, etc. With the proper steps, macOS can be reinstalled without erasing user files.
Back Up Your Data
Before reinstalling macOS Big Sur, it is crucial to back up your data. A backup protects you from losing important files, documents, photos, and other data in case anything goes wrong during the reinstallation process. As Apple Support notes, you can use Time Machine to back up your Mac and then restore your personal files after reinstalling macOS.
Make sure you have an external hard drive or other disk with enough storage capacity to hold a full backup of your data. Connect it to your Mac. Then use Time Machine to perform a complete backup. The initial backup may take hours depending on your disk speed and amount of data. It is important not to disconnect the backup disk until the process is fully complete.
You can also use iCloud to back up your most important files, if you have sufficient iCloud storage available. Enable iCloud Backup in System Preferences > Apple ID > iCloud. Then check that all your important folders like Documents and Desktop are included in the backup.
Overall, comprehensively backing up your data before reinstalling macOS Big Sur gives you important protection. It allows you to restore your files if anything goes wrong. So take the time to secure your data before proceeding.
Download macOS Big Sur
To download the latest macOS Big Sur installer on your Mac, open the App Store app and search for “macOS Big Sur”. The installer will be available as a free download from Apple (https://apps.apple.com/gb/app/macos-big-sur/id1526878132?mt=12). Click the “Get” button and the installer will download to your Applications folder.
If you need to download the installer on a different Mac, you can download the full installer package directly from Apple’s servers. Follow the steps outlined in this article to download the full Big Sur installer: (https://mrmacintosh.com/macos-big-sur-full-installer-database-download-directly-from-apple/). This allows you to download the installer without needing to get it from the App Store.
Make sure you have enough free disk space for the large installer file. The installer will be over 12GB in size.
Create a Bootable Installer
To reinstall macOS Big Sur without losing data, you will need to create a bootable USB installer drive. This drive allows you to boot your Mac from the USB and reinstall macOS. Here are the steps to create a bootable installer:
1. Insert at least an 8GB USB flash drive into your Mac. The flash drive will be erased, so make sure it doesn’t contain any important files.
2. Launch Terminal, which can be found in the Utilities folder in Applications.
3. Enter the following command in Terminal, replacing “MyVolumeName” with the name of your USB drive:
sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolumeName
4. You will be prompted to enter your administrator password. Enter it and press Return.
5. The drive will be formatted and the installer downloaded. This may take some time to complete. When done, you’ll see a message that the installer was successfully created.
6. Once complete, eject the USB installer drive. It is now ready to be used to reinstall macOS Big Sur (Source).
Boot From the Installer
Once you’ve created the macOS Big Sur bootable installer drive, you’ll need to boot your Mac from the drive in order to reinstall the operating system. Here’s how to boot into the installer drive:
First, connect the bootable installer drive to your Mac via USB. Make sure it is the only drive connected. Then restart your Mac and immediately hold down the Option key after you hear the startup chime. This will bring up the boot picker menu.
Next, select the installer drive from the boot picker menu. The drive will likely be labeled as “Install macOS Big Sur” or “EFI Boot”. Then click the upward arrow or press Return to boot from the selected drive.
Your Mac will now boot up to the macOS Utilities window. From here, you can erase your drive and proceed with reinstalling Big Sur as normal. The installer will automatically format the drive, so you don’t need to erase in advance unless you prefer to do so.
For more details, refer to Apple’s support document on creating a bootable installer.
Reinstall macOS
To reinstall macOS without losing data, you will first boot your Mac from the macOS installer and then go through the process of reinstalling the operating system. Here are the steps:
- With the bootable macOS installer connected, restart your Mac and hold down the Option key immediately after you hear the startup chime. This will bring up the boot menu.
- Select the macOS installer drive from the boot menu. Your computer will boot to the Recovery System.
- In the macOS Utilities window, click Reinstall macOS. Click Continue.
- Follow the onscreen prompts to begin the installation process. Make sure to select your existing drive when asked where to install macOS.
- The macOS installer will update system files and reinstall the operating system while preserving your data and user settings. This process can take up to an hour.
- Once the installation is complete, your Mac will reboot to a fresh copy of macOS with your files and settings intact.
Following these steps will reinstall a clean version of macOS without deleting your user data. Just be sure to backup first in case anything goes wrong.
Restore From Backup
Once you have reinstalled macOS Big Sur, you can restore your data from a backup. To restore from a Time Machine backup:
Connect the external hard drive containing your Time Machine backups. Open Migration Assistant on your newly upgraded Mac, then follow the onscreen instructions. Migration Assistant will allow you to select which backup to restore from, as well as which files and settings you wish to transfer.
Migration Assistant can transfer your user accounts, user files, applications, and some settings and preferences from a Time Machine backup. Make sure to select all the items you want to restore during this process (1). Once the restoration is complete, you can double check that your important files, apps, and settings are present on your Mac.
If you backed up an Intel-based Mac, and are restoring to an Apple silicon Mac, Migration Assistant will automatically convert the data to work on the new system.
Reinstall Apps
After reinstalling macOS, you will need to redownload your apps from the App Store. Here are some tips for getting your apps back smoothly:
Open the App Store on your Mac and go to the Purchases tab. Here you will see a list of all the apps you have previously downloaded. You can download any of them again for free.
If you have the “Automatically download apps purchased on other devices” setting enabled in App Store preferences, any apps you’ve downloaded on other devices like an iPhone will automatically download to your Mac as well. This makes redownloading apps much easier.
For apps that the App Store thinks are already installed, you may need to delete the app from your Launchpad first. Then when you go back to the Purchased section in the App Store, it will allow you to download the app again [1].
Downloading large app bundles like Microsoft Office can take time. Be patient and let the downloads complete.
If you have any issues getting apps to redownload, check for App Store updates and restart your Mac. This can often resolve minor glitches.
Troubleshooting
Reinstalling macOS Big Sur can sometimes run into issues. Here are some common problems and potential fixes:
macOS Big Sur getting stuck during installation – This is often caused by insufficient storage space. Make sure there is at least 15GB of free space before starting the installation process.
Installation failed with an error message – Error messages during installation may indicate a problem with the installer file itself. Try downloading the installer again and make sure you have the latest version.
“An error occurred while preparing the installation” – This usually means the disk cannot be modified. Go to Disk Utility and erase the disk before trying to reinstall macOS. Make sure to backup your data first.
Installation takes a long time and seems frozen – Be patient, as the Big Sur installation can take over an hour on some systems. Let it run and see if it eventually completes.
Mac gets stuck on a black screen – Force restart your Mac (press and hold the power button) and try the installation again. The installer may have frozen.
To troubleshoot, first try restarting your Mac and re-running the installation. If issues persist, erase your disk drive fully before attempting to install again. Check Apple’s support site for the latestBig Sur troubleshooting tips.
Conclusion
In summary, reinstalling macOS Big Sur can provide several benefits without losing your personal data. By creating a bootable installer and booting from it, you can perform a clean install of Big Sur which refreshes the operating system files. This can resolve problems caused by outdated, corrupted or incompatible system files. Reinstalling Big Sur is a fairly straightforward process that does not delete your user data, as long as you properly back up your files first. Once the OS is reinstalled, you can restore your data from your backup. With a fresh install of Big Sur, you may see performance improvements, resolutions of software issues, and an overall more stable macOS experience.