[This section is still work in progress]
It appears that older, purchased operating system installers are no longer displayed in the new Mojave App Store.
When testing the El Capitan installer with a published URL, it will appear in the App Store. However, when the download is requested, it is no longer "not valid for this Mac", it now states "The requested version of macOS is not available".
Some more tests are required – contributions welcome – to see if other OS versions are similarly removed. For these we may need direct links that I do not currently have.
The easiest way, if available, is to use your shopping history in the App Store.
If you have ever installed an OS X version, this list will still be available to you. This should also include public beta versions.
The version available in this list is always the latest version of its type – d. H. 10.7.5, 10.8.6 … 10.11.6
Image heavily modified to show only operating system versions.
Note that either download or install will be displayed, depending on whether you have the installer file stored locally or not – even on a non-boot drive.
Sierra itself has now disappeared from the buying history of all. However, Apple keeps Sierra fully available, even though High Sierra is not available. No Apple ID required.
If the version you are trying to download is older than the Mac you are trying to download the version of, the store will not allow the download.
[looking for workarounds to this part – edits welcome – I can’t test this as the newest Mac I have is a 2012 Mac Pro]
Possible workarounds must be tested –
How to download Lion from Mountain Lion again?
If you're trying to upgrade an older computer with Snow Leopard or Lion, you can get a special version of El Capitan on the App Store
This version of El Capitan is for users with OS X Snow Leopard or
OS X Lion, who wants to upgrade to macOS High Sierra. If you are
Snow Leopard or Lion and enjoy upgrading to High Sierra,
You must first install El Capitan. This version of El Capitan can
also be installed on computers that are not compatible with High
Note the last sentence … This version can not be installed on any computer Not currently on Snow Leopard or Lion, If the machine can run High Sierra.
This means that it is a very specific resource and not a general "prison-free card" for anyone who wants El Capitan.
If you need to reinstall from Recovery and have previously run Sierra 10.12.4 or higher, there are now 3 options available.
Hold the appropriate key combination to the start chimes …
- Cmd ⌘ R
Install the latest MacOS installed on your Mac without upgrading to a newer version
- Opt ⌥ Cmd ⌘ R
Upgrade to the latest MacOS compatible with your Mac
- Shift ⇧ Opt ⌥ Cmd ⌘ R
Install the macOS supplied with your Mac or the closest version that is still available.
The first two options are available for all Macs older than Lion (around 2009).
It is also possible to create a bootable USB disk for the recovery disk with this Apple tool – Apple KB: OS X: About the Recovery Wizard
If you have access to an older point release of an operating system, 10.11.0, and so on, and you want to upgrade, you can download Apple's Combo Updaters, which includes everything you need to get straight to the latest point release in a single step. z. 10.11.6
Google is good at finding them because the hit is the top hit
Combo-Update 10.11 etc but here are links to some
El Capitan 10.11.6
High Sierra 10.13.6
If you need to create a bootable USB flash drive to install it
How do I make a bootable USB flash drive on a Mac?
How do I create a bootable Mac USB drive with Windows?
Find a friend who can access the download[[[[recommended]
Find a torrent / sharing site[[[[not recommended]
There is no "legitimate" way to download macOS from a Mac other than a Mac. It requires the Apple App Store.
Note: You can not use a Time Machine backup to return to an operating system that is older than the operating system of the latest backup on this Time Machine drive.
This means that you must swap out the Time Machine drive before you can upgrade the operating system so you can always restore to a previous Backup & OS with a Time Machine backup. This is because when the Time Machine drive detects the new operating system, the older operating system is no longer used. You can still manually extract data from the Time Machine, but you can not use it to restore to the older operating system.