Restart your Mac while holding the Option (⌥) key, then select the USB drive from the boot menu.
While High Sierra is no longer prominently featured in the App Store, you can still access it through specific official channels.
Now that you have prepared your installation media, follow these steps to install the operating system on the target Mac. Step 1: Boot from the USB Installer Shut down the target Mac completely. download+macos+high+sierra+10136+dmg+mac+install
Ensure you are using an original Apple internal SSD during setup. Third-party NVMe SSDs frequently fail firmware validation updates unless a genuine Apple drive is present to accept the initial motherboard update block. If you need help with any particular step, let me know:
Use the arrow keys to select and press Enter . Restart your Mac while holding the Option (⌥)
If you need to perform a "clean install" (wiping the drive first), you should create a bootable USB drive (16GB+ recommended).
macOS High Sierra 10.13.6 Update: Recommended for users currently on 10.13.5. Step 1: Boot from the USB Installer Shut
Finding a legitimate, safe source to can be frustrating due to Apple’s deprecation of older software links. However, by using the official softwareupdate Terminal command or the hidden App Store URL, you can still obtain the final build of High Sierra (10.13.6 / 17G66) without resorting to piracy.
