Upgrading from 10.13 to 10.15 is not just a patch; it's a major system overhaul. You must have a backup in case the installation fails. Connect an external hard drive. Open Time Machine in System Preferences. Click Back Up Now .
Your Mac will now begin writing the installation files and will eventually restart. The screen may go black or show an Apple logo with a progress bar multiple times. This is completely normal and can take anywhere from 30 minutes to over an hour. Troubleshooting Common Upgrade Issues "The disk uses the Mac OS Extended format" how to update macos high sierra 10.13.6 to 10.15
Before you begin, there are three critical things you need to know: Upgrading from 10
If you can tell me what or how much free space you have, I can offer more tailored advice. AI responses may include mistakes. Learn more Share public link Open Time Machine in System Preferences
macOS Catalina runs on the following Macs (most Macs that ran High Sierra can run Catalina):