This is not yet known, but it happens with the final version of macOS High Sierra installer as well as with some of the beta versions.

Why do some users get a small incomplete version of macOS High Sierra installer from the App Store? You can confirm that you have the complete Install macOS High Sierra.app application by getting info on the file, the complete installer should be around 5.2 GB rather than the tiny 19 MB incomplete installer that requires additional downloads. The source of this patcher application is a MacRumors Forums * The “macOS High Sierra Patcher” application is intended for those with unsupported Macs and Hackintosh users, but any Mac user can use the app to be able to download the complete installer file from Apple servers. Locate the “Install macOS High Sierra.app” file you downloaded, it will be the complete installer application with the full Contents/Resources/ toolkit available.The patcher app will notify you when the download is complete, when it is done downloading quit out of the patcher app.Confirm that you want to download the complete macOS High Sierra install application, and then point it to a location to save on the local hard drive.

Launch “MacOS High Sierra Patcher” and ignore everything about patching, instead pull down the “Tools” menu and choose “Download MacOS High Sierra”.Go to here and download the High Sierra patcher application*.Warning: this method relies on a third party tool from an unverified third party source, if you are not comfortable with using unvetted and unverified software, and if you do not understand the risks associated with using potentially dubious software, do not follow this process. How to Download the Full “Install macOS High Sierra.app” Application This tutorial will show you a workaround trick that allows Mac users to download the full macOS High Sierra “Install macOS High Sierra.app” file at 5.2 GB with the complete installer tool set and all dmg files and associated Install macOS High Sierra.app/Contents/Resources/ tools, rather than the tiny incomplete truncated installer at 19 MB.

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