Apple’s certificate for High Sierra expired in late 2019. The installer checks the timestamp and thinks it is corrupt.
Before the era of sleek "Dark Modes" and Control Centers, High Sierra was the gold standard for stability. Even years after its release, users seek out the for several critical reasons:
You are trying to install High Sierra on a Mac that originally shipped with a newer OS, or your firmware is outdated. mac os x 10.13 high sierra dmg download
The script does not modify Apple’s files; it acts as a download manager for Apple’s own servers.
If you are running macOS 10.15 or newer, you can bypass the App Store interface using a simple Terminal command to download the full installer directly from Apple's servers. Apple Support (found in /Applications/Utilities/). Paste the following command and press Enter: Apple’s certificate for High Sierra expired in late 2019
An 8GB or larger USB flash drive (name it "MyVolume").
If you are on a Windows PC looking to set up a VM, the App Store link will not work for you. You will need to find a trusted third-party source for the DMG. Even years after its release, users seek out
Note: This will download the "Install macOS High Sierra" app directly to your Applications folder.