How To - Update Macos High Sierra 10136 To 1015

Upgrading your Mac from to macOS Catalina (10.15) is a major step that modernizes your system while introducing critical changes, such as the complete transition to 64-bit applications. Step 1: Verify Hardware Compatibility

Use the built-in Time Machine utility to back up your entire system to an external drive. This is critical as the upgrade may reformat your drive to the APFS file system.

macOS Catalina does not support 32-bit apps . Tools like Go64 can help you identify which applications will stop working after the update. macOS Catalina - Technical Specifications - Apple Support

If using a laptop, plug it into a power source during the update. Step 2: Essential Pre-Update Checklist