With OS X El Capitan (10.11) for the Mac, the upgrade install is the default method of performing an installation. This means the installer application launches automatically after downloading the OS from the Mac App Store. Before you start the installation, quit the installer and take care of some important setup details.
What You Need to Run OS X El Capitan
Before downloading and installing OS X El Capitan, determine whether the Mac is equipped to run the OS. Review the El Capitan minimum system requirements to learn what kind of hardware you need and which devices support the OS.
Once you have determined that the Mac meets the requirements, you're almost ready to proceed. First, take steps to ensure that the Mac is ready to install the OS and experience a trouble-free installation process.
Back Up Existing Data
Make sure your current data is safely backed up. Installing a new OS makes major changes to a Mac, including deleting some system files, replacing other files, setting new file permissions, and adjusting preference files for system components and apps.
If anything goes wrong during the install process, the Mac may lose critical data. The risk isn't worth it, especially when a basic backup is easy to perform.
Types of Installations Supported by OS X El Capitan
Gone are the days of complex install options, such as Archive and Install, which backed up the system then performed an upgrade install. Apple now provides two installation methods: the upgrade install, which is the process covered in this guide, and a clean install.Upgrade Install overwrites the current version of OS X, replaces outdated system files, installs new system files, resets file permissions, updates Apple-supplied apps, and installs new Apple apps. There are more steps involved in the update process. The one thing an upgrade install won't do is change your user data.Clean Install cleans the target volume of the system and user data. This is usually done by erasing the target volume, then installing OS X El Capitan. Using the clean install option leaves you with a Mac that is similar to a new Mac fresh out of the box. No third-party apps are installed, no users are created, and user data is deleted. When a Mac starts up after a clean install, the initial setup wizard walks you through the process of creating a new administrator account. The clean install option is an effective way of starting over. It may be a good method of installing a new OS if you experienced problems with your Mac that you cannot resolve.
Even though the installer does not touch user data, most major system updates include changes to Apple apps. It's likely that when you first run apps, such as Mail or Photos, the app will update associated user data. In the case of Mail, your mail database may be updated. In the case of Photos, your older iPhoto or Aperture image library may be updated. This is one reason why it's a great idea to perform a backup before running the OS X installer. This way, you can recover needed data files that may be updated or potentially cause problems.
Check Your Startup Drive for Errors
Check the startup drive for errors and repair file permissions. Make sure the Mac's startup drive is in good shape and that the existing system files have the correct permissions. Use Disk Utility to repair hard drives and disk permissions.
How to Download OS X El Capitan From the Mac App Store
OS X El Capitan can be found in the Mac App Store as a free upgrade for OS X Snow Leopard and later. If your Mac meets the minimum system requirements for El Capitan but has an earlier OS, purchase OS X Snow Leopard from the Apple store. Then, follow the instructions to install Snow Leopard on the Mac. Snow Leopard is the oldest version of OS X that can access the Mac App Store.
Download OS X 10.11 (El Capitan) From the Mac App Store
Use a web browser to navigate to the El Capitan upgrade page on the Apple App Store. Scroll down to step No. 4 and select Download OS X El Capitan. The download will begin. Once complete, the OS X El Capitan installer starts on its own.
At this point, quit the installer and create a bootable OS X El Capitan installer on a USB flash drive. This step is optional but can be helpful if you have multiple Macs to update. You can use the bootable USB flash drive to run the installer on any Mac.
Start the Upgrade Process Using the OS X El Capitan Installer
After you've backed up your data and made sure the Mac meets the requirements for running El Capitan, download the OS X El Capitan installer from the Mac App Store. If needed, created a bootable copy of the OS X El Capitan installer on a USB flash drive. You can now start the installer by launching the Install OS X El Capitan app in the Applications folder on your Mac.
When the installer opens and displays the Install OS X window, select Continue.
Read the license terms for OS X, then select Agree.
The Install OS X window displays the current startup volume as the destination for the installation. If this is the correct location, select Install.
If this is not the correct location, and multiple disks are attached to the Mac, select Show All Disks, then choose the destination disk from the available choices. Select Install when ready.
If you're performing a clean install on another volume, refer to our Clean Install OS X El Capitan guide.
Enter your administrator password, then select OK.
The installer copies a few files to the destination volume and restarts the Mac. A progress bar displays, with an estimate of the remaining time. It may take a while.
Once the progress bar is complete, the Mac restarts and begins the OS X El Capitan setup process, where you provide configuration information to set up your personal preferences.
OS X El Capitan Setup Process for an Upgrade Install
At this point, the El Capitan installation has finished and displays the OS X Login screen. This happens even when the previous version of OS X was set to bring you directly to the Desktop. You can use the System Preferences pane, later on, to set the user login environment to the way you want it.
Configure OS X El Capitan User Settings
After OS X El Capitan is installed, update the User settings to configure the system to fit your needs.
Enter your administrator account password, then press the Enter key or select the right-facing arrow next to the password field.
OS X El Capitan asks for your Apple ID. Supplying this information allows the setup wizard to automatically configure several user preferences, including syncing with your iCloud account. You don't have to supply your Apple ID at this point. You can choose to do it later or not at all. However, providing this information makes the setup process move quickly. Provide your Apple ID password, then select Continue.
A sheet appears asking if you wish to use Find My Mac, a service that allows you to locate your Mac using geolocation tracking. This service also locks and erases the contents of your Mac if it is stolen. You don't have to enable this function if you don't wish to. Select Allow or Not Now.
The terms and conditions for using OS X, iCloud, Game Center, and related services display. Read the license terms, then select Agree.
A sheet appears asking you to confirm the agreement. Select Agree.
The next step asks if you wish to set up iCloud Keychain. This service syncs your Apple devices to use the same keychain, which contains passwords and other information you have decided to save in the keychain. If you were using the iCloud Keychain in the past and wish to continue, select Set Up iCloud Keychain. If you haven't used the iCloud Keychain service in the past, select Set Up Later, then set up and use iCloud Keychain. The process is complex, so you should have a good understanding of the security issues before proceeding. Make your selection, then select Continue.
The setup wizard finishes the configuration process and displays the new OS X El Capitan desktop.
Try out the new operating system. You may find with a fresh OS that some things don't work the same way. OS X El Capitan may have reset some system preferences to the defaults. Take time to explore the System Preferences pane to get your Mac back to the way you like it.
If you like, return to some of the optional items you might have skipped during the setup, such as setting up iCloud and iCloud Keychain.