How to Upgrade Install macOS Sierra Safely on Your Mac

Upgrading retains your user data and most apps

What to Know

  • Back up your Mac. Download the installer from Apple. Open the macOS installer. Select Continue, scroll through the terms, and choose Agree.
  • Select the Mac startup drive and select Install. Provide your admin password and choose the Add Helper button.
  • The installer copies files to the drive and displays a progress bar. After the Mac restarts, run Setup Assistant to finish the installation.

This article explains how to upgrade install macOS (10.12) Sierra safely on your Mac.

Backup, Backup, Backup

It's not likely that anything will go wrong during the upgrade install of macOS Sierra. Even so, there are two reasons to make a usable backup before proceeding:

  • Stuff happens; it's that simple. You never know what will happen when you upgrade. Maybe the power will go out, maybe a drive will fail, or the download of the OS could be corrupt. Why take the chance of having your Mac restart from an aborted install and end up with just a gray or black screen staring you in the face when having a current backup makes it possible for you to recover from such catastrophes quickly.
  • You don't like the new OS. Perhaps you don't like how some new feature works; the old way was better for you. Maybe you have an app or two that doesn't work with the new OS, and you need to use those apps. Having a backup or a clone of your existing version of OS X ensures you can go back if the new OS doesn't meet your needs for whatever reason.

Upgrade or Clean Install of macOS Sierra?

This guide shows you how to perform an upgrade install, which overwrites your current version of the operating system to install macOS Sierra. The upgrade installs new versions of system files and Apple-supplied apps and services. However, it leaves all your user data intact, letting you work right away with the new OS without having to import or restore data from a backup or a previous version of the OS.

For most users, the upgrade install is the best choice for updating, but macOS Sierra also supports a clean install process.

The clean install erases all content from your Mac's startup drive, including the existing OS and all of your user files. It then installs a clean copy of the macOS with no older data involved. You start over from scratch.

Begin the Upgrade Install Process

The first step is the backup. Make sure you have a current Time Machine or equivalent backup of all your Mac's data.

It is also a good idea to have a clone of your current Mac startup drive so that you can go back to the current version of OS X should you ever need to.

With the backup/clone out of the way, check your Mac's startup drive for any problems it may have using Disk Utility.

How to Download macOS Sierra

Initially, macOS Sierra was available from the Mac App Store as a free upgrade to anyone using OS X Snow Leopard or later on their Macs. It is no longer in the Mac App Store, but you can download Sierra from Apple online.

When the macOS Sierra download is complete, the installer launches automatically. Quit the installer immediately, and optionally create a bootable copy of the macOS Sierra installer that you can use on any Mac at any time without having to go through the download process.

Perform the Upgrade Install of macOS Sierra

After you create a backup, download the macOS Sierra installer, and optionally create a bootable copy of the installer on a USB flash drive. With all that out of the way, it's time to install Sierra.

  1. The macOS Sierra installer should be open on your Mac. If you quit the installer to make a bootable copy, restart the installer by opening the Applications folder and double-clicking the Install macOS Sierra item.

  2. The Installer window opens. To proceed with the installation, click the Continue button.

  3. The software licensing agreement displays. Scroll through the terms and click the Agree button.

  4. A drop-down sheet asks if you agree to the terms. Click the Agree button on the sheet.

  5. The installer displays the Mac's startup drive as the target for the upgrade install. It is usually named Macintosh HD, although you may have given it a custom name. If the drive selection is correct, click the Install button. Otherwise, click the Show All Disks button, select the correct disk for the installation, and then click the Install button.

  6. A dialog box opens, asking for your administrator password. Provide the information and then click the Add Helper button.

  7. The installer copies files to the target drive and displays a progress bar. After the files are copied, your Mac restarts.

    macOS Sierra install screen

    Don't worry if the restart takes a while. Your Mac is going through the installation process, copying some files and removing others. Eventually, a status bar displays with a time estimate.

Run Setup Assistant to Finish the macOS Sierra Installation

With the installation complete, your Mac is ready to run the setup assistant to configure the last few macOS Sierra options.

If you configured your Mac to require a login, your Mac presents a normal login window. Enter your login information and continue to the macOS setup process. If your Mac is set to auto-log you in, you jump right to the macOS Sierra setup process.

Because this is an upgrade install, most of the setup process is performed for you automatically, using the information from the previous version of the operating system. You may see different setup items other than those listed here. That leaves only a few items to configure before you can use macOS Sierra.

  1. The setup process starts by displaying the Sign In with Your Apple ID window. If you would like to leave everything as it is and go to the desktop, select Set Up Later. This may require you to turn on iCloud services and set up iCloud Keychain and other services from System Preferences when you decide you need them. There's no harm in using the Set Up Later option; it only means you'll manually enable services, one at a time, when you need them.

  2. Enter your Apple ID password and click the Continue button if you would rather have the setup assistant take care of configuring the available services that make use of your Apple ID,

  3. The Terms and Conditions for using macOS software and various iCloud services are displayed. Click the Agree button.

  4. A sheet drops down, asking you to confirm that you agree to the terms and conditions. Click the Agree button.

  5. The setup assistant configures the iCloud account information and then asks if you want to set up iCloud Keychain. You can choose to set this up later using the process outlined in Guide to Using iCloud Keychain.

  6. Next, you are presented with two settings regarding how to use iCloud for storing documents and images from your Photos library:

    • Store files from Documents and Desktop in iCloud Drive: This option uploads the files from your Documents folder and the desktop to your iCloud Drive automatically and keeps all your devices synced to the data. You'll also see an estimate of the amount of space required in iCloud to perform this task. Be careful, as Apple only provides a limited amount of free storage in your iCloud Drive, although you can purchase additional storage space as needed.
    • Store photos and videos in iCloud Photo Library: This uploads the images and videos in your Photo Library to iCloud automatically and keeps this data synced with all your Apple devices. Just like the Documents option, iCloud storage space beyond the free tier has an additional cost.

    Make your selections by placing check marks in front of the options you want to make use of and click Continue.

    macOS Sierra upgrade installation setup assistant
  7. The setup assistant completes the setup process and takes you to your Mac’s desktop.

You have successfully upgraded your Mac to macOS Sierra.


One of the new features of macOS Sierra is the inclusion of Siri, the personal digital assistant commonly in use with the iPhone. Siri can perform many of the same tricks that iPhone users have enjoyed for years, but Siri for the Mac goes even further.

macOS Sierra desktop

About macOS Sierra

Apple announced macOS Sierra at WWDC 2016, with a public beta release in July of 2016, and the full release on September 20, 2016. This guide supports the official full release version of macOS Sierra (10.12).

macOS Sierra brings with it minimum requirements that leave some old Mac models out in the cold.

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