How to Update/Reinstall macOS Without Losing Data

This page outlines the complete process for updating and installing the latest macOS versions, such as Big Sur, Catalina, Mojave, and so on, without losing any data. If you're seeking a detailed guide, please follow this page to successfully install your desired macOS version on your computer now:

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Applies To: macOS Big Sur, macOS Catalina, macOS Mojave, macOS High Sierra, macOS Sierra, or earlier Mac operating systems

The necessity to update or reinstall macOS typically arises after a new operating system release, when your Mac is running slowly, or in the event of a system crash. When it comes to reinstallation, users' primary concern is often the potential loss of data on their computer.

The good news is that if you meticulously follow the instructions to update your Mac Operating System, the likelihood of losing data on your Mac is minimal. This is because a reinstallation essentially creates a fresh copy of the OS, but your existing files stored on your Mac remain intact. Consequently, as long as you do not opt to erase your startup disk during the reinstallation process, your files should be preserved. However, "minimal" does not equate to zero risk; there is still a chance, albeit small, of losing some data.

Then, how to reinstall macOS without losing any data? To provide a double assurance for the valuable data on your Mac, you can create a backup of your Mac's files before reinstallation or equip your Mac with a data recovery tool that can salvage your data post-reinstallation.

Preparations You Need to Make Before Reinstalling macOS

To reinstall macOS on your computer seamlessly, follow these steps to ensure your Mac is ready for the new macOS update: 1. **Backup Your Data**: Before any major update, it's crucial to back up your important files and data. You can use Time Machine or an external drive to create a backup. 2. **Check for Available Updates**: Go to "System Preferences" > "Software Update" to see if there are any pending updates for your current macOS version. Install them first. 3. **Free Up Disk Space**: Make sure you have enough storage space for the new installation. Remove unnecessary files, apps, and downloads. You can use the "About This Mac" > "Storage" management tools to help optimize space. 4. **Disable Security Software**: Temporarily disable any antivirus or security software to prevent potential conflicts during the installation process. 5. **Sign Out of Accounts**: Sign out of Apple ID, iCloud, and other accounts to avoid any issues with syncing during the update. 6. **Disconnect External Devices**: Remove any non-essential peripherals like printers, USB devices, and external drives, as they might interfere with the installation. 7. **Create a Recovery Drive**: If your Mac doesn't have macOS Recovery, create a bootable installer drive using another Mac or the Internet Recovery feature. 8. **Prepare for Installation**: Restart your Mac and press the appropriate key (usually Command + R) during startup to access the macOS Recovery. From there, choose "Reinstall macOS" and follow the on-screen instructions. By following these guidelines, you'll be well-prepared for a smooth macOS reinstallation experience.

• Ensure there is at least 2GB of memory and 8.8 GB of storage space available on your Mac
• Make sure your Mac has a minimum of 45% battery remaining
• Connect your Mac to the internet or a WiFi network
• Update all your Mac applications to their latest versions
• Back up all your personal data, and create backups of your current Mac data using Time Machine

Remember to back up your Mac to an external hard drive to prevent system update failures or unexpected issues. Then, follow the detailed guide below to reinstall macOS using macOS Recovery mode. This allows you to reinstall macOS, restore files from Time Machine, repair or erase a disk, and more.

How to Update and Reinstall macOS Without Losing Data

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Step 1. Start up your Mac from macOS Recovery

1. Turn on your Mac and immediately press and hold "Command + R", "Option + Command + R", or "Shift + Option + Command + R". 2. Release the keys when the Apple logo, a spinning globe, or a firmware password prompt appears.

Step 2. In the Utilities window, choose "Reinstall macOS" and click "Continue".

Step 3. Follow the on-screen instructions to select the hard drive you want to install the operating system on and commence the installation process.

Step 4. Avoid putting your Mac to sleep or closing its lid during the installation. It's typical for your Mac to restart several times or display a blank white screen while the Mac OS is being reinstalled. Simply wait patiently for the process to complete.

If data loss occurred after you reinstalled macOS, follow the next section to recover your missing files.

Recover Lost Data After macOS Reinstallation

If you've backed up your Mac prior to the reinstallation, you can restore your data from Time Machine, an external hard drive, or another location, depending on the backup method you employed. If you haven't made any backups for your Mac, you'll require professional Mac data recovery software, such as Data Recovery Wizard, to perform data recovery. With this tool's assistance, you can easily retrieve data lost due to macOS reinstallation:

Step 1. Search for missing files

Select the disk location where you lost your files (it can be an internal HDD/SSD or an external hard drive). Click the "Search for lost files" button.

注意:在进行数据恢复之前，最好从左侧边栏点击“磁盘备份”为您的HDD/SSD创建备份，以防止进一步的数据丢失。备份后，软件可以从磁盘备份中恢复数据，您可以再次使用HDD或SSD。

Step 2. Review the scanning results

This software will immediately scan your selected disk volume and display pictures, documents, audio, videos, and emails on the left pane.

Step 3. Select the file(s) and recover Select the desired file(s) you wish to recover from the scan results, and then initiate the recovery process.

Click on the data to preview it, and then hit the "Recover" button to restore them.

There are plenty of data recovery tools out there, but one of the best Mac data recovery tools, Data Recovery Wizard, is our top choice. It fully supports all macOS systems, including the latest Big Sur, Catalina, Mojave, High Sierra, Sierra, El Capitan, Yosemite, and more. With just a few simple clicks, it enables you to recover all lost data. You can easily restore office files, music, videos, emails, and other archives on your own.