I have MacBook Mid 2010 running macOS 10.13.6, and I plan to put a SSD in it to give it a few extra years in light use for the family or relatives (I also have Mac mini Late 2009 needing SSD update).
In April 2018 I successfully downloaded and archived macOS 10.13.4-17E199 full installer from App Store. I also archived all downloadable updaters to macOS 10.13.6 so basically I'm all set. Until the installers' certificates expire, that is.
https://tidbits.com/2016/03/02/previously-downloaded-os-x-installers-no-longer-work/
But after April 2018 the macOS 10.13 High Sierra download repeatedly gives only the small stub installer. I would still like to have an option to make a bootable newer version flash drive, if possible.
(BTW I can still successfully download full installers of OS X 10.6 Snow Leopard, OS X 10.8 Mountain Lion and OS X 10.11 El Capitan from their App Store's Purchased tab).
Now, this is not a very big deal: even if all I had was a MacBook Mid 2010 or Mac mini Late 2009 with a broken disk, I could use (Option-)Command-R and install using internet recovery (I tested and it works even with the Mac mini 2009). But I'd prefer an off-line installer because such large internet downloads are unpredictable and take lots of time.
At the moment "macadmin-scripts" seems to be the best workaround to prepare an off-line installer (you must run it on hardware compatible with the version of macOS for which you are attempting to obtain an installer although you may also have success running the script in a VM).
https://github.com/munki/macadmin-scripts
Basically you just click the green "Clone or download" button on that page to download ZIP, expand it, and drag "installinstalmacos.py" in it to the Terminal window (make sure to set the correct path). Answer which version you want and after a while a .dmg with the full installer is in the in your home folder (or in some other working directory):
sudo python /path/to/installinstalmacos.py
Also "macOS High Sierra Patcher" can download macOS 10.13 High Sierra full installer. But there are some aspects I don't like:
I do trust the developer but it isn't as transparent as "macadmin-scripts" to show what tools are used and where it downloads the software from.
At least with my setup the download repeatedly failed a few times until it finally somehow succeeded (the same thing happened during a few days time).
Currently it still downloads 1+ year old macOS 10.13.6-17G65 while "macadmin-scripts" downloads current macOS 10.13.6-17G66 from Jan 2019.
BTW the build number of the OS is at the ProductBuildVersion inside /System/Library/CoreServices/SystemVersion.plist in the mounted BaseSystem.dmg. You can use the GUI or the following commands to show the version number (make sure to set the correct path):
hdiutil attach "/path/to/Install macOS High Sierra.app/Contents/SharedSupport/BaseSystem.dmg"
cat "/Volumes/OS X Base System/System/Library/CoreServices/SystemVersion.plist"
And finally, at least on my Mac mini Late 2009 the prepared flash installer did boot OK but the patched High Sierra install failed to boot (SIP disabled, Mac OS Extended (Journaled), post install patches applied and caches rebuilt. This is not a high priority to me so I did not ask the developer about it).
http://dosdude1.com/highsierra/
http://osxdaily.com/2017/09/27/download-complete-macos-high-sierra-installer/
All other methods currently only download the small stub macOS 10.13 High Sierra installer:
Fail: App Store download using up-to-date macOS 10.11.6/10.13.6 logged in or out to App Store without or with Shift/Option key and/or using "sudo softwareupdate --clear-catalog" and/or setting DNS to 8.8.8.8.
Fail: Download the stub installer, use it to download the missing "/macOS Install Data", copy its contents to the stub installer's "Install macOS High Sierra.app/Contents/SharedSupport", using Apple recommended Terminal command make a bootable flash drive which boots OK. But when actually trying to install, the installer stops to error "The installer resources were not found". Also VMware Fusion refuses to install from it. Maybe the downloaded files should be processed further with this method?
I don't know why App Store currently hides versions like macOS 10.13 High Sierra and downloads the stub installer. Maybe Apple wants to steer users to the Internet Recovery using Mac HW as a big dongle instead making off-line installers easily available.
