: Re-download the DMG file from a different source, or use a different USB port/drive to re-create the bootable installer. APFS Conversion Failures
Here is everything you need to know about finding the DMG, creating a bootable drive, and installing it.
However, Apple no longer prominently features this legacy OS in the Mac App Store. So, how do you get the official file? And more importantly, how do you perform a clean installation (wiping your drive and starting fresh) without running into errors?
Select your internal startup disk (usually named Macintosh HD) and click .
Why are people still downloading this 2017 OS?
This method is ideal for users who plan to install High Sierra directly on the same Mac used for downloading. However, if you need to create a bootable USB installer for a different Mac or if your current Mac is running a newer macOS version that prevents the download, you will need alternative methods.
These third-party sources are particularly valuable when Apple's App Store prevents downloads on newer Macs. However, users should exercise caution and verify file integrity when downloading from any third-party source. Authentic High Sierra DMG files are typically around 4.9 GB in size.
Obtaining operating system files from third-party websites or torrent networks exposes your machine to malware, adware, and compromised system security. Always use official Apple channels to fetch the installation files. Method A: Downloading via the Mac App Store (Recommended)
If you wish to keep your files, simply select without erasing the drive in Disk Utility. Troubleshooting & Common Issues