How to use macOS Recovery to restore the operating system on your Mac

Source: iMore

If you’ve encountered a problem with macOS, the solution might be to reinstall the system on your Mac. This can be done by any Mac owner, but it can be a little bit complicated. You’ll need to put your Mac into macOS Recovery, which gives you tools to diagnose problems on your Mac, as well as reinstall the operating system.

Here’s how to reinstall macOS using Recovery mode.

Entering macOS Recovery

macOS Recovery has tools at its disposal that allow you to diagnose problems with your Mac’s hard drive, reinstall macOS, and restore from a Time Machine backup. You can enter Recovery by pressing certain key combinations. The combination you choose will determine which version of macOS will be installed on your system when you select Reinstall macOS.

• Press Command — R to install the latest version of macOS that was installed on your Mac without installing a later version.
• Press Options — Command — R to upgrade to the latest version of macOS that’s compatible with your Mac.
• Press Shift — Option — Command — R to install the version of macOS that came with your Mac, or the version closest to it that’s still available.

How to check your startup disk with Disk Utility in macOS Recovery mode

The first thing you’ll want to do is make sure your Mac’s startup disk is healthy. You’ll need to use Disk Utility to do that.

1. Click Disk Utility when in macOS Recovery.
2. Click Continue.
3. Click on your Mac’s startup drive in the Disk Utility sidebar. It should be the drive at the top of the sidebar if there are multiple drives.
4. Click First Aid.
5. Click Run. First Aid will run, checking the health of your Mac’s drive. This process could take a little while.
6. Click Done.
7. Click Disk Utility in the Menu bar.
8. Click Quit Disk Utility.

How to erase your startup disk in macOS Recovery mode

If you need to start completely fresh, then you’ll want to erase your startup disk using Disk Utility. If you want the content on your Mac to stay intact, skip to the next section.

1. Click on your startup disk in the Disk Utility sidebar.
2. Click Erase.
3. Click the Format drop-down menu.
4. Click on the format you want to use for your drive. If you’re running macOS High Sierra or later on a Mac with an SSD, your choices will be some form of APFS.
5. Click Erase. Your drive will proceed to be erased.

How to reinstall macOS while in Recovery mode

The next step is to reinstall macOS.

1. Click Reinstall macOS.
2. Click Continue.
3. Click Continue.
4. Click Agree.
5. Click Agree.
6. Click on the drive on which you wish to install macOS.
7. Enter your Apple ID and password if you’re asked to, though you might not be.
8. Click Install.

Your Mac will now go through the normal macOS installation process, eventually restarting. If you’re starting from scratch, you’ll need to set up your Mac from scratch.

Questions?

If you have any more questions about reinstalling macOS on your Mac, let us know in the comments.

Updated December 2019: Everything is up to date through macOS Catalina.

Restore your Mac from a backup

Use Migration Assistant to transfer files from your Time Machine backup to your Mac.

If you made a Time Machine backup of your Mac, Migration Assistant can use that backup to restore your personal files, including apps and everything in your user account.

If you prefer to restore just a few files or earlier versions of those files, learn how to use Time Machine to restore specific files.

Use Migration Assistant

1. If you need to reinstall macOS, do that before continuing. For example, if your Mac starts up to a flashing question mark, you need to first reinstall macOS.
2. Make sure that your Time Machine backup disk is connected to your Mac and turned on.
3. Open Migration Assistant on your Mac. It’s in the Utilities folder of your Applications folder.
   If your Mac starts up to a setup assistant, which asks for details like your country and network, continue to the next step, because the setup assistant includes a migration assistant.
4. When asked how you want to transfer your information, select the option to transfer from a Mac, Time Machine backup, or startup disk. Then click Continue.
   
5. Select your Time Machine backup, then click Continue.
   
6. Choose a backup and click Continue.
   
7. Select the information to transfer.

In this example, John Appleseed is a macOS user account. If it has the same name as an account already on your Mac, you’re prompted to either rename the old account or replace the one on your Mac. If you rename, the old account will appear as a separate user on your Mac, with a separate home folder and login. If you replace, the old account will delete and then replace the account on your Mac, including everything in its home folder.

Click Continue to start the transfer. Large transfers might need several hours to complete.

Restart your Mac in macOS or Windows

After installing Microsoft Windows on your Mac, you can choose whether your Mac starts up in macOS or Windows.

How to start up in macOS from Windows

1. From the notification area on the right side of the Windows taskbar, click to show hidden icons.
2. Click the Boot Camp icon .
3. From the menu shown, choose Restart in macOS.
   If you haven’t installed the latest Boot Camp updates, you might get the message ”Could not locate the OS X boot volume.»
   

Or use Startup Manager as your Mac starts up:

1. Restart your Mac from the Start menu in Windows.
2. Press and hold the Option (or Alt) ⌥ key as your Mac begins to restart.
3. Select your Mac startup volume (Macintosh HD) in the Startup Manager window, then press Return or click the up arrow:
   

How to start up in Windows from macOS

• Use Startup Manager to choose your Windows (Boot Camp) volume during startup.
• Or select your Boot Camp volume in Startup Disk preferences, then restart.

Learn more

• If you’re having difficulty using VoiceOver or another screen reader to complete these steps, please contact Apple Support.
• Learn how to install Windows 10 on your Mac.

Information about products not manufactured by Apple, or independent websites not controlled or tested by Apple, is provided without recommendation or endorsement. Apple assumes no responsibility with regard to the selection, performance, or use of third-party websites or products. Apple makes no representations regarding third-party website accuracy or reliability. Contact the vendor for additional information.

What to do before you sell, give away, or trade in your Mac

Back up your data, then restore to factory settings by turning off certain features and services, erasing your Mac, and reinstalling macOS.

Moving to a new Mac? Before taking these steps, you can use Migration Assistant to move your files from the old Mac to your new Mac.

Create a backup

Make sure that you have a current backup of your important files. Learn how to back up your Mac.

Sign out of iTunes in macOS Mojave or earlier

If you’re using macOS Mojave or earlier, open iTunes. From the menu bar at the top of the screen or iTunes window, choose Account > Authorizations > Deauthorize This Computer. Then enter your Apple ID and password and click Deauthorize.

Learn more about deauthorizing computers used with your iTunes account.

Sign out of iCloud

If you’re using macOS Catalina or later, choose Apple menu  > System Preferences, then click Apple ID. Select Overview in the sidebar, then click Sign Out.

If you’re using macOS Mojave or earlier, choose Apple menu  > System Preferences, click iCloud, then click Sign Out.

You will be asked whether to keep a copy of your iCloud data on this Mac. You can click Keep a Copy, because you’re erasing your Mac later. Your iCloud data remains in iCloud and on any other devices that are signed in to iCloud with your Apple ID.

Sign out of iMessage

If you’re using OS X Mountain Lion or later, open the Messages app, then choose Messages > Preferences from the menu bar. Click iMessage, then click Sign Out.

Reset NVRAM

Shut down your Mac, then turn it on and immediately press and hold these four keys together: Option, Command, P, and R. Release the keys after about 20 seconds. This clears user settings from memory and restores certain security features that might have been altered.

Optional: Unpair Bluetooth devices that you’re keeping

If your Mac is paired with a Bluetooth keyboard, mouse, trackpad, or other Bluetooth device that you plan to keep, you can unpair it. This optional step prevents accidental input when the Mac and device have separate owners but remain in Bluetooth range of each other.

If you’re unpairing Bluetooth input devices from a desktop computer such as an iMac, Mac mini, or Mac Pro, you must plug in a USB keyboard and mouse to complete the remaining steps in this article.

To unpair a Bluetooth device, choose Apple menu  > System Preferences, then click Bluetooth. Move your pointer over the device that you want to unpair, then click the remove (x) button next to the device name.

Erase your hard drive and reinstall macOS

The best way to restore your Mac to factory settings is to erase your hard drive and reinstall macOS.

After macOS installation is complete, the Mac restarts to a setup assistant that asks you to choose a country or region. To leave the Mac in an out-of-box state, don’t continue setup. Instead, press Command-Q to shut down the Mac. When the new owner turns on the Mac, the setup assistant guides them through the setup process.

No matter the model or condition, we can turn your device into something good for you and good for the planet: Learn how to trade in or recycle your Mac with Apple Trade In.

How to reinstall macOS

Use macOS Recovery to reinstall the Mac operating system.

Start up from macOS Recovery

Apple silicon

Turn on your Mac and continue to press and hold the power button until you see the startup options window. Click the gear icon labeled Options, then click Continue.

Intel processor

Make sure that your Mac has a connection to the internet. Then turn on your Mac and immediately press and hold Command (⌘)-R until you see an Apple logo or other image.

If you’re asked to select a user you know the password for, select the user, click Next, then enter their administrator password.

Reinstall macOS

Select Reinstall macOS from the utilities window in macOS Recovery, then click Continue and follow the onscreen instructions.

Follow these guidelines during installation:

• If the installer asks to unlock your disk, enter the password you use to log in to your Mac.
• If the installer doesn’t see your disk, or it says that it can’t install on your computer or volume, you might need to erase your disk first.
• If the installer offers you the choice between installing on Macintosh HD or Macintosh HD — Data, choose Macintosh HD.
• Allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart and show a progress bar several times, and the screen might be empty for minutes at a time.

After installation is complete, your Mac might restart to a setup assistant. If you’re selling, trading in, or giving away your Mac, press Command-Q to quit the assistant without completing setup. Then click Shut Down. When the new owner starts up the Mac, they can use their own information to complete setup.

Other macOS installation options

When you install macOS from Recovery, you get the current version of the most recently installed macOS, with some exceptions:

• On an Intel-based Mac: If you use Shift-Option-Command-R during startup, you’re offered the macOS that came with your Mac, or the closest version still available. If you use Option-Command-R during startup, in most cases you’re offered the latest macOS that is compatible with your Mac. Otherwise you’re offered the macOS that came with your Mac, or the closest version still available.
• If the Mac logic board was just replaced, you may be offered only the latest macOS that is compatible with your Mac. If you just erased your entire startup disk, you may be offered only the macOS that came with your Mac, or the closest version still available.

You can also use these methods to install macOS, if the macOS is compatible with your Mac:

• Use the App Store to download and install the latest macOS.
• Use the App Store or a web browser to download and install an earlier macOS.
• Use a USB flash drive or other secondary volume to create a bootable installer.