Upgrading your Mac from macOS High Sierra (10.13.6) to macOS Catalina (10.15) introduces a modernized operating system. This jump replaces 32-bit app support with a strict 64-bit architecture, splits iTunes into dedicated media apps, and adds enhanced security features. Because this is a major system transition rather than a minor patch, proper preparation and execution are critical to avoid data loss. Phase 1: Verify Hardware Compatibility
Never initiate a major OS upgrade without a current backup. If the installation fails or power cuts out mid-update, your data could be corrupted. Connect an external hard drive to your Mac. Open > Time Machine . Click Select Backup Disk and choose your external drive.
If the App Store route throws errors or fails to download, you can upgrade using macOS Recovery Mode over the internet. Shut down your Mac completely. how to update macos high sierra 10136 to 1015
This error happens when the digital security certificate of an older installer has expired. To fix this, delete the installer from your Applications folder, clear your Mac App Store cache, and redownload the file to obtain a fresh copy with updated certificates. Stuck on the Apple Logo
. With a click, the App Store finally revealed the 8GB prize: macOS Catalina Chapter 3: The Long Descent (Download) The owner clicked Upgrading your Mac from macOS High Sierra (10
macOS High Sierra 10.13.6 macOS Catalina 10.15 , you must first verify your hardware's compatibility and back up your data, as this update removes support for all 32-bit applications. If your Mac is officially supported, you can download the installer directly from the Mac App Store 1. Verify Compatibility and Requirements
Once the installer finishes, you’ll see a welcome screen. Phase 1: Verify Hardware Compatibility Never initiate a
Do not touch power, do not force shut down. If stuck on a progress bar for over 2 hours, then troubleshoot (see Step 6).
Identify essential productivity tools—such as or legacy Adobe Creative Suite packages—that are strictly 32-bit.
CRITICAL: macOS Catalina does not support 32-bit apps. If you rely on old versions of Microsoft Office or Adobe Creative Cloud, they will stop working after the update.