Your Mac will restart to begin the installation process. A progress bar and an Apple logo will appear on the screen. The process can take anywhere from 30 minutes to over an hour depending on your hard drive speed. Your screen may go black or restart multiple times; this is completely normal. Do not close the lid or turn off the machine until the login screen appears.
Before downloading anything, you must confirm that your Apple hardware officially supports macOS Catalina. The following Mac models are compatible with macOS 10.15: 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
Restart your Mac, hold Cmd+R to enter Recovery Mode. Use Disk Utility to run First Aid on your startup disk. Then try the installer again.
You need a minimum of 12.5 GB of available storage if upgrading from High Sierra. Apple recommends keeping up to 20 GB free to prevent installation stalls. Memory: At least 4 GB of RAM is required. how to update macos high sierra 10136 to 1015
Never attempt a major operating system upgrade without a current backup. If the installation is interrupted or a drive error occurs, you risk losing your data. Connect an external hard drive to your Mac. Open from your System Preferences. Click Select Backup Disk and choose your external drive.
If you're trying to update to a very specific version (e.g., for compatibility reasons), you might need to use the macOS Recovery mode or download the installer directly from the Mac App Store. However, Apple usually encourages users to stay on the latest version of macOS for security and feature updates.
Use Time Machine to back up all your data to an external hard drive. If something goes wrong, you can restore your system exactly as it was. Your Mac will restart to begin the installation process
Open the Mac App Store on High Sierra and install any pending updates for your existing software. This ensures your 64-bit apps are in their most stable state prior to the OS migration. Step 5: Download and Install macOS Catalina
macOS Catalina 10.15 requires one of these Macs:
If necessary, run a final Time Machine backup to ensure your new system is backed up. What to Do If Your Mac is Too Old Your screen may go black or restart multiple
Before any major OS upgrade, use Time Machine to back up your data to an external drive. Updates can fail, and data loss is a real risk.
Some Macs on High Sierra can directly install macOS Big Sur (11) or Monterey (12) without installing Catalina first, provided they meet hardware requirements.