You’re staring at a spinning beachball on a 2015 MacBook Pro that used to be fast. Or maybe you’re a creative pro whose favorite plugin just broke because Ventura decided it didn't like legacy code. It happens. We’ve all been there, regretting that "Install Now" button. Honestly, the biggest lie in tech is that newer is always better. Sometimes, the best way forward is actually going backward.
But here is the kicker: Apple doesn't make it easy. If you search the App Store for "Mojave" or "High Sierra," you’ll probably get a big fat zero results. They want you on the latest, most secure, most "memoji-filled" version of macOS. If you need to download old macOS versions, you have to know the secret handshakes and the direct links that Apple hides behind its support walls. It's a bit of a scavenger hunt, but it’s totally doable if you have a little patience and a formatted USB drive.
Why the App Store is gaslighting you
Try searching for macOS Big Sur in the App Store right now. Seriously, try it. You won't find it. Apple hides these installers once a new major version comes out. Why? Because maintaining security patches for five different operating systems is a logistical nightmare for them. They’d rather you just buy a new M3 Max and call it a day.
But your hardware has a "sweet spot." A 2012 Mac Mini runs like a dream on Catalina but chugs like an old steam engine on anything newer. If you're trying to revive an old machine, you need the specific software it was designed to handle. You've got to circumvent the standard "Update" tab in System Settings. That tab is designed to push you forward, never back.
The official "Secret" links
Apple actually maintains a support page that most people miss. It’s a repository of links that open hidden App Store entries. If you are looking for anything from macOS Sonoma back to High Sierra, you can usually find the direct App Store hooks.
However—and this is a big "however"—these links only work if your current Mac is compatible with the version you're trying to download. If you're on a brand new M2 MacBook Air, the App Store will flat-out refuse to download a copy of El Capitan. It knows. It’s smart like that. To get around this, you often need a "bridge" machine—an older Mac that can still technically run the software you’re hunting for.
Getting your hands on the actual installers
So, how do you actually get the file? For versions like macOS Monterey, Big Sur, and Catalina, the App Store is still your primary source, provided you use the direct links found on Apple’s support site. You click the link, it launches the App Store, and you hit "Get."
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Then, System Settings will pop up and ask if you’re sure you want to download an older version. Yes, you’re sure. Stop asking.
But what about the really old stuff? If you’re looking for OS X El Capitan, Yosemite, or Sierra, Apple provides these as .dmg disk images instead of App Store downloads. You download the DMG, open it, and run the .pkg installer inside. This doesn't actually install the OS; it just unpacks the "Install macOS" app into your Applications folder. It’s a weird, two-step dance that confuses almost everyone the first time they do it.
Terminal: The power user's shortcut
If you’re comfortable with a command line, there’s a much faster way. Apple included a tool called softwareupdate in macOS. You can actually see what’s available by typing:softwareupdate --list-full-installers
If the version you want is on that list, you can pull it down directly with:softwareupdate --fetch-full-installer --full-installer-version 12.6.1
(Just swap that version number for whatever you're looking for). This bypasses the App Store's clunky UI entirely. It’s clean. It’s fast. It makes you feel like a hacker from a 90s movie.
The "Certificate Expired" nightmare
Here is a fun fact that will make you want to throw your computer out a window: Apple’s installers have expiration dates. No joke. They use digital certificates to verify that the software hasn't been tampered with. Every few years, those certificates expire.
If you try to run an old installer you’ve had sitting on a hard drive for three years, you’ll probably get an error saying the application is "damaged" or "can't be verified." It’s not damaged. It’s just that the digital "use-by" date has passed.
How do you fix it? The "old school" trick is to disconnect from the internet and change your system clock. If you’re trying to install an OS from 2016, set your Mac’s date to sometime in 2016. It tricks the installer into thinking the certificate is still valid. It sounds stupid, but it works surprisingly often. Just remember to set the clock back once you’re done, or your web browser will freak out because it thinks it's living in the past.
Creating the bootable USB (The only way to fly)
You can't just run an older installer from inside a newer version of macOS. It won't let you. It’ll give you a "This version is too old" warning. To actually download old macOS versions and install them, you almost always need a bootable USB drive.
You need a drive with at least 16GB of space.
- Format it as Mac OS Extended (Journaled).
- Name it "MyVolume" (or something easy to type).
- Use the
createinstallmediacommand in Terminal.
The command looks something like this:sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
You’ll have to type your password (you won’t see the characters as you type, which is normal) and then wait about 10 to 20 minutes. Once it’s done, you have a physical "rescue" drive. You can plug this into any compatible Mac, hold the Option key (or the power button on Apple Silicon) during startup, and boot directly into the installer. This is the cleanest way to do a "wipe and reload."
Apple Silicon vs. Intel: The big divide
If you are on an M1, M2, or M3 Mac, forget about anything older than Big Sur. You can’t run Intel-native versions of macOS on Apple Silicon. It’s a hardware limitation. You can try to use virtualization software like UTM or Parallels, but even then, you’re limited. If you’re trying to run Snow Leopard for some old-school 32-bit apps, you’re going to need an actual Intel Mac. You can find old 2012 MacBook Pros for cheap these days, and they are basically the "classic cars" of the Mac world—highly customizable and capable of running a huge range of OS versions.
Safety and Third-Party Sources
Look, you’re going to find sites like "https://www.google.com/search?q=All-The-MacOS-Downloads.com" or random torrents. Be careful. Seriously. Operating systems are the literal foundation of your digital life. If someone injects a keylogger into a custom ISO or DMG, you’re handing over the keys to your kingdom.
Always try to get the file from Apple’s servers first. Even if you use a third-party tool like the "MIST" (macOS Installer Super Tool) or the "OpenCore Legacy Patcher" downloader, these tools are generally safer because they usually pull the files directly from Apple's own Content Delivery Networks (CDNs). They are just providing a better interface for the download than Apple does.
Why bother anyway?
You might be wondering if it's worth the hassle. For most people, no. But if you have a specific piece of hardware—like a FireWire audio interface or a legacy Adobe CS6 suite—that requires an older kernel, then downloading an old macOS version is the only way to keep that gear out of the landfill. It’s an act of digital preservation.
Also, some older versions were just... better? Snow Leopard is still heralded as the peak of Mac stability. Mojave was the last version to support 32-bit apps. There are valid, non-nostalgic reasons to want these versions.
Actionable steps for a successful downgrade
If you’re ready to take the plunge, don't just start clicking. Follow a plan so you don't end up with a bricked machine.
- Backup everything twice. Use Time Machine for your files, but also drag-and-drop your most important documents to an external drive or cloud service. Time Machine backups from a newer OS often cannot be fully restored to an older OS.
- Identify your "Target" OS. Look up your Mac model on EveryMac.com to see the "Maximum OS" and "Original OS" it shipped with. Don't try to go lower than what the machine originally shipped with; it won't have the drivers for the hardware.
- Grab the installer now. Even if you don't plan on installing it today, download the version you want and keep it on a dedicated drive. Apple has a habit of making these links harder to find every year.
- Check your FileVault settings. If you’re going to wipe your drive, make sure you know your passwords. If you have a T2 security chip (Macs from 2018-2020), you may need to enter Recovery Mode and "Allow booting from external media" before your USB installer will even work.
- Keep an Ethernet cable handy. Sometimes Wi-Fi drivers aren't included in the base installer for older versions, especially if you’re using a newer Mac with older software. Being able to plug directly into your router can save you hours of troubleshooting.
Once you have your USB drive ready and your files backed up, restart the Mac, hold the Option key, and select the installer. Format the internal drive as APFS (for High Sierra and later) or Mac OS Extended (for anything older), and let it run. It might take a few reboots. Just let it do its thing. Before you know it, you’ll be looking at a desktop that feels snappy again, free from the bloat of modern updates that your hardware was never meant to carry.