Post-Catalina, your login keychain often breaks because the user ID structure changes. Before updating, open (Applications > Utilities). Right-click on the “login” keychain and select “Change Settings for Keychain ‘login’.” Turn off “Lock after X minutes of inactivity.”
Best for most users.
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: how to update macos high sierra 10.13.6 to 10.15
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. Post-Catalina, your login keychain often breaks because the
“macOS could not be installed on your computer” error. Not all Macs that run High Sierra can handle Catalina
At least 18.5GB of available storage for the upgrade.
However, if you specifically need Catalina (e.g., for 32-bit app compatibility in a dual-boot setup or legacy software), this guide gives you everything required to make the jump safely from High Sierra 10.13.6 to Catalina 10.15.