How to Upgrade from OS X El Capitan to OS X High Sierra

Overview and Quick Answer

Upgrading from OS X El Capitan to OS X High Sierra is straightforward if your Mac meets the compatibility and hardware requirements. In short, most Macs from 2012 and later can perform this upgrade, but you must back up your data first using Time Machine or another method. This guide explains how to verify eligibility, prepare your system, execute the update, and confirm a clean install, with expectations for what changes and what stays the same.

Compatibility and Requirements Checklist

Confirm your Mac is supported and has sufficient free space before you begin. High Sierra drops support for older 32-bit EFI and some earlier models. Meeting the minimum hardware and firmware requirements reduces the risk of an interrupted update or failed install.

Supported Mac Models

• iMac (Mid 2012 or later)
• MacBook (Early 2015)
• MacBook Air (Mid 2012 or later)
• MacBook Pro (Mid 2012 or later)
• Mac mini (Late 2012 or later)
• Mac Pro (Late 2013)

Minimum System Requirements

• OS X El Capitan 10.11.6 or later installed
• At least 20 GB of available storage
• An Administrator account

Back Up Your Mac

Backing up is the most critical preparatory step. A successful system update still carries a small risk of data corruption or configuration issues. Use Time Machine to create a full backup to an external drive, or ensure you have a current, restorable copy of your key data. If your startup disk becomes damaged during the upgrade, you will rely on this backup to restore files and settings.

Recommended Backup Steps

• Connect an external drive with enough capacity for your Mac’s used storage.
• Open System Preferences > Time Machine and select the backup disk.
• Click Back Up Now and wait for the initial backup to finish.
• Verify the backup by opening Time Machine and browsing a few files.

Check Software and Firmware Readiness

Ensure apps and firmware are in good shape before starting the update. Outdated firmware or incompatible applications can cause hangs or restarts. Updating critical system firmware, such as EFI and SMC firmware, is especially helpful for hardware-related issues on older Macs.

Quick Pre-Update Checklist

• Update apps from the App Store where possible.
• Check vendor sites for firmware updates if you experience hardware quirks.
• Confirm your Apple ID credentials are available for App Store purchases during the update.

How to Upgrade to High Sierra

Once your Mac is compatible and backed up, you can install High Sierra using the Mac App Store. The App Store provides the download and install process, and you can resume an interrupted download if needed. During installation, your user files and applications remain in place, though Apple recommends not using the Mac while the update proceeds.

Step-by-Step Installation

1. Open the Mac App Store on your Mac running El Capitan.
2. Search for OS X High Sierra and click Get or Update.
3. Enter your Apple ID if prompted and confirm the download.
4. Once downloaded, the installer will launch automatically; follow onscreen instructions.
5. Do not turn off or restart your Mac during the installation process.

After the Upgrade: Verification and Troubleshooting

After the upgrade completes, verify that core functions are working and review system information to confirm you are running High Sierra. If the upgrade fails or the Mac reverts to El Capitan, you may need to reinstall or repair permissions using Disk Utility, depending on your Mac model and the symptoms you observe.

Post-Upgrade Checks

• Choose the Apple menu > About This Mac and confirm the version reads macOS High Sierra.
• Check System Preferences for any prompts to update additional components.
• Test key functions such as Wi-Fi, sound, display resolution, and external devices.
• Open Time Machine and verify that your user files are present and accessible.

Installation Outcomes and What to Expect

High Sierra introduces an updated file system (APFS) for SSDs, refined security features, and modest performance improvements. Not all drives convert to APFS automatically, and you can remain on the Mac OS Extended (HFS Plus) format if you prefer. Your applications, documents, and system settings usually survive the upgrade, but occasional preferences or helper tools may need reinstallation or resetting.

What Changes and What Stays the Same

When to Delay or Seek Support

If your Mac fails to boot after the upgrade or shows persistent errors, pause further troubleshooting and back up important data immediately using an external drive or Migration Assistant. For firmware-level issues or Drive Kit errors, consult Apple Support or an authorized service provider. If your Mac is on the edge of the supported specifications, upgrading may expose hardware limitations that were previously masked by El Capitan.

Summary Checklist

• Verify model compatibility and OS X version (El Capitan 10.11.6+).
• Back up with Time Machine or other reliable method.
• Ensure at least 20 GB of free storage.
• Use the Mac App Store to download and install High Sierra.
• Confirm the upgrade in About This Mac and test core functionality.

Pricing Considerations

Upgrading from El Capitan to High Sierra was distributed for free through the Mac App Store, so there is typically no direct cost for the OS upgrade. Any relevant expenses relate to hardware checks, potential external storage for backups, or professional support if you encounter issues. Apple occasionally offered promotional pricing on storage or hardware around major releases, but those offers are not part of the standard upgrade path.