How to Update macOS High Sierra 10.13.6 to 10.15 (macOS Catalina)

This method retains user data, accounts, and applications.

Use a utility like Go64 to check which of your current apps are 32-bit. You will need to find 64-bit updates or replacements for these before upgrading. Step 3: Back Up Your Data

Before running the installer:

Your Mac will save the installation files and restart. During the installation process: