In High Sierra, updates appear in the App Store, but major version upgrades often require a direct link or a specific search. Open the on your Mac. Search for "macOS Catalina" .
Upgrade process (recommended steps)
Because you are running High Sierra, you may not see Catalina in "Software Update" within System Preferences. You must use the App Store: macOS - How to Upgrade - Apple (SI) how to update macos high sierra 10136 to 1015
The bar filled up. The screen went black again, then burst into a "Welcome" animation in multiple languages. The setup assistant appeared. He selected his region, signed in with his Apple ID, and agreed to the terms. In High Sierra, updates appear in the App
Stuck at version 10.13.6, need 10.15. Not… - Apple Community Upgrade process (recommended steps) Because you are running
"Easy enough," Elias muttered. He opened the System Preferences pane, expecting to see a "Software Update" button that would whisk him away to the newer version.