How To Update Macos High Sierra 10.13.6 To 10.15 📥

As of late 2024/2025, Apple no longer provides security updates for Catalina. While this guide explains how to do the upgrade, you should consider upgrading further to a newer supported OS (like Monterey or Ventura) if your Mac allows it. This guide focuses strictly on the High Sierra → Catalina path.

Not all Macs that run High Sierra can handle Catalina. Your hardware must meet the following official requirements: MacBook: Early 2015 or newer. MacBook Air: Mid 2012 or newer. MacBook Pro: Mid 2012 or newer. Mac mini: Late 2012 or newer. iMac: Late 2012 or newer. iMac Pro: 2017 or newer. Mac Pro: Late 2013 or newer. System Specs:

Before any major upgrade, perform a full backup using the Apple Time Machine Guide . Connect an external hard drive to your Mac. Go to . Click Select Backup Disk and choose your external drive. how to update macos high sierra 10.13.6 to 10.15

If the download won’t start, check your internet connection and restart the App Store.

Ensure you have the (Security Update 2020-006 or later). As of late 2024/2025, Apple no longer provides

This update is a major leap. You are moving from an operating system released in 2017 (High Sierra) to one released in 2019 (Catalina). This update fundamentally changes how your Mac handles system files, apps (introducing Project Catalyst), and security (splitting the hard drive into two volumes). As of 2025, Catalina is considered “end-of-life” by Apple (no more security updates), but many users need it to run legacy software or bridge the gap to a newer OS. Proceed with caution.

| Problem | Likely Solution | |--------|----------------| | “macOS could not be installed on your computer” | Restart, hold for Recovery, run Disk Utility > First Aid , then retry. | | Installer is stuck on “less than a minute remaining” | Wait up to 2 hours. If stuck, force restart (hold power button). It often recovers. | | Wi-Fi not working after upgrade | Reset NVRAM: Shut down, power on and hold Cmd+Option+P+R for 20 seconds. | | “This disk is locked” error | Boot to Recovery, open Terminal, type resetpassword (no space), then use the reset tool to unlock the disk. | | App crashes immediately | Likely a 32-bit app. Check About This Mac > System Report > Software > Legacy Software . | Not all Macs that run High Sierra can handle Catalina

Only do this if you have a full backup.