Your Mac will restart. The installation process usually takes 30 to 60 minutes. during this time. Troubleshooting & Alternative Paths
To update macOS High Sierra 10.13.6 to macOS 10.15 Catalina, you must first ensure your hardware is compatible and your data is safely backed up. Catalina is a major transition as it . 1. Check Hardware Compatibility how to update macos high sierra 10136 to 1015