How To Update Macos High Sierra 10.13.6 To 10.15 [extra Quality] Jun 2026

Major operating system upgrades carry an inherent risk of data loss. A robust backup strategy is mandatory.

October 2023 (updated for historical context) Prepared For: Users running macOS High Sierra 10.13.6 Subject: Feasibility, prerequisites, and step-by-step procedure for upgrading to macOS 10.15 (Catalina)

Before downloading any files, you must ensure your specific Mac model officially supports macOS Catalina 10.15. Attempting to force an installation on unsupported hardware can result in system instability or a failure to boot. how to update macos high sierra 10.13.6 to 10.15

Open your Safari browser and visit Apple's official support page for older macOS versions, or click this direct Mac App Store link for macOS Catalina .

You will see a black screen with an Apple logo and a progress bar. Major operating system upgrades carry an inherent risk

If you’re still running , you’re likely missing out on years of performance improvements, security patches, and modern features. Moving to macOS Catalina (10.15) represents a significant leap forward, introducing Sidecar (iPad as a second display), Screen Time, redesigned Apple Music and Podcasts apps, and the death of iTunes in favor of Finder-based device syncing.

With your preparation complete, you are ready to download and install Catalina. Attempting to force an installation on unsupported hardware

Double-click Install macOS Catalina.app in your Applications folder. Click “Continue” and agree to the software license.

The easiest and safest method is using Apple's built-in utility: Connect an external hard drive to your Mac. Open System Preferences and click Time Machine . Click Select Backup Disk and choose your external drive.