This is the safest and recommended method. It downloads the Install macOS High Sierra.app directly from Apple's servers.
If you don’t see High Sierra: This means your Apple ID never downloaded it when it was current. In that case, use Method 3 below.
This is the safest, fastest, and most reliable method. Apple maintains a hidden catalog of older installers accessible only via the command line. You do not need an existing macOS recovery partition to do this.
Apple maintains a legacy support page that hosts direct .dmg files for OS updates, but these are usually combo updaters (updating from 10.13 to 10.13.6) rather than the full 10.13.6 clean installer. Download Mac Os High Sierra 10.13.6 Dmg
If you only need the High Sierra 10.13.6 Combo Update DMG (to patch an existing High Sierra install), use this official link:
macOS High Sierra 10.13.6 Combo Update
Important: This is an update DMG (approx 2.8GB). It cannot create a bootable USB installer from scratch. It requires a functioning High Sierra base installation. This is the safest and recommended method
If you obtain the installer legitimately, you can verify its integrity:
Do not rely on random MD5 hashes from forums.
Once you have extracted InstallESD.dmg from the official installer, simply having the DMG on your hard drive is useless. You need to burn it to a USB drive. Here is the professional method using createinstallmedia. This is the safest, fastest, and most reliable method
Mac OS High Sierra (version 10.13) is a former major release of Apple’s desktop operating system, first launched in September 2017. The 10.13.6 update (released July 2018) was the final version of High Sierra, including crucial security patches and APFS (Apple File System) improvements.
A DMG (Disk Image) file is a common macOS format for distributing software or system installers. Searching for “Download Mac OS High Sierra 10.13.6 DMG” typically indicates a user wants to:
However, High Sierra no longer receives security updates (final patch: November 2020). Using it on internet-connected machines is not recommended for general users.