Tutorial : How to download old macOS installers
Old collections of macOS installer disk images you used to keep may now be worthless, and Apple has made it even harder to find any downloadable copies before macOS Monterey. However, there are still good reasons to get the old operating system, and here's how to do it.
Apple really wants you to use macOS Monterey. If that means you have to buy a new Mac, they'll find a way to deal with their anxiety. Partly because of this, and partly to let newcomers know that this is the current version of macOS and that the company has long hidden previous versions.
If you've been using a Mac for a long time, you've probably learned how convenient it is to keep a copy of each macOS when you upgrade. Even though they're easily accessible, they're still large, so it's much easier to use a local copy.
Unfortunately, that handy bunch of macOS installers you collected on that old external drive became worthless on October 24, 2019.
As of that date, any old macOS you still have a copy of will not work. You can't install macOS from them because the security certificates on them have expired by then.
However, any old macOS installers you can download from Apple now will work. As the annual release cycle passes, we're at the point where we can download the last four versions.
Or more specifically, download them when you know exactly where to look. apple keeps the latest older installers in the App Store, but hides them.
You'll never see them listed, and you usually won't be able to find them through a direct search. You must read Apple's support documentation before you can get the link that will magically open the installer in the App Store.
This is now true for the last four versions, while the three versions before that required a separate solution.
But first, why should you bother
Don't use older versions of macOS because, for example, you're running low on drive space and OS X Tiger is attractive because it takes up less space.
(Even if you can find the Tiger installer on Apple's website, modern Macs won't run it. Instead, they report that it comes from an unidentified developer. This may also have something to do with the October 24 expiration date; if so, it's hard to see how Apple has been doing anything for the OS since it began nearly 15 years ago.)
Even if you use a lesser prehistoric version, don't do it unless you have to.
That's not to say it's hard or somehow risky for your Mac, but it may not make sense. If your Mac is physically capable of running macOS Monterey, then you're almost certainly better off updating it to that version.
While Apple has supported Macs for longer than it seems, there are still plenty of machines that can't be updated to Montery, and certainly not to Apple Silicon. which is fine, because you'll probably leave them on whatever they're currently running.
But it's easy to eventually get older Macs that are running well but could use some updating. not all the way to Monterey, or even Big Sur, but maybe to the High Sierra, maybe El Capitan, maybe the Mojave.
You should update to every new version of macOS. it's worth it for the features, security and reliability.
And the more you can bring your old Mac up to date, the longer you'll be able to get useful work out of it.
You just need to find the old macOS installer.
How to find High Sierra via Big Sur
Use these links to get to any of the last four versions of macOS. In each case, the link will take you to the hidden App Store entry for the macOS installer.
In each case, the App Store will also tell you if the version you want cannot be installed on the Mac you are using. apple notes that you cannot install any macOS on a machine that is older than the one that came with your Mac.
Therefore, you must click on these links on the Mac that is accepting the download. These links will take you to the download page.
How to find old macOS installers
Choose from the options below to get official macOS updates and get them directly from Apple. Clicking will begin the download.
In each case, Apple recommends that you first check the latest version of your Mac that you can run and then make a thorough, repeated backup of that Mac.
Apple also notes that you cannot install a macOS version on top of a higher version. You can't go back. If you really need a hobby, you can erase your Mac and start over with an older macOS installation if you're so inclined for software compatibility or similar reasons.
And it's easy to imagine the need to update older machines to make them last longer. And, it increases the security of the Internet.