After a major upgrade, you may need to sign back into iCloud. Go to > Apple ID and ensure you are logged in. Check that services like iCloud Drive, Photos, and Keychain are syncing properly.
Your Mac may open the Software Update pane in System Preferences to begin the download. Confirm that you want to download the software. 2. Run the Installer
Choose between Light Mode, Dark Mode, or Auto Mode (which shifts based on the time of day).
Wait for the list to load. Click on the column header to sort the apps.
Also, check for firmware updates for your Mac (these sometimes get bundled with macOS updates). Keeping your current OS as updated as possible (10.13.6 is fine, but ensure it’s the latest security update) smooths the transition.
Updating your Mac from macOS High Sierra (10.13.6) to macOS Catalina (10.15) is a significant upgrade that brings a modern interface, improved security, and new features like Sidecar and Apple Music. However, because this jump involves moving from older 32-bit architecture support to a strictly 64-bit system, it requires careful preparation.
If the App Store freezes or refuses to download, go to Apple’s official support download page:
This is arguably the biggest "gotcha" of upgrading to Catalina. entirely. If any of your essential apps are 32-bit, they will simply refuse to open after the upgrade.
: Use Time Machine to create a full system backup before proceeding.
Your Mac may open the Software Update pane in System Preferences to pull down the file.
Your Mac is now fully updated to macOS Catalina 10.15. You can verify this by going back to to check the version number. Open the App Store and click the Updates tab to install any remaining security patches or supplemental updates released for Catalina.
Select your preferred visual style between Light Mode, Dark Mode, or Auto (which switches based on the time of day).
You’re now on macOS 10.15. But the work isn’t over. Here’s what to do immediately.
You need a minimum of 15 GB to 20 GB of available storage on your internal drive. If you are running low, clear out your Downloads folder, delete old device backups, or move large media files to an external drive.