If you’re still sitting on a Mac running 10.12, you're basically living in a digital time capsule. It’s a stable place to be, sure, but the internet is moving on without you. Sites are breaking. Security certificates are expiring. Honestly, the jump to 10.13 isn't just about getting new emojis or a slightly faster Safari; it’s about moving your entire file system into the modern era. When Apple dropped High Sierra, they changed the literal foundation of how your Mac stores data.
Upgrading macOS Sierra to High Sierra is the bridge between the old "spinning drive" era and the modern SSD world. If you've been procrastinating because you're afraid of losing files or bricking your late-2011 MacBook Pro, I get it. Operating system updates feel like open-heart surgery for your computer. But staying on Sierra is becoming a liability.
The APFS Factor: Why This Specific Jump Matters
Most people think macOS updates are just UI tweaks. They aren't. With High Sierra, Apple introduced the Apple File System (APFS). Before this, Macs used HFS+, a system designed decades ago when hard drives had physical platters that spun around like a record player. APFS is built for Flash and SSD storage.
What does that actually mean for you? It means copying a file happens almost instantly. It means your Mac calculates folder sizes in a blink rather than making you wait for that little gray progress bar. If you have an SSD, this upgrade is the single best thing you can do for the longevity of your hardware.
However, there is a catch.
If you are running an older Mac with a mechanical Hard Disk Drive (HDD) or an early Fusion Drive, APFS wasn't originally forced upon you, but later versions of the installer tried to push it anyway. This caused some slowdowns for folks with older, physical platters. You have to know what hardware you’re packing before you hit that "Update" button. Check your "About This Mac" section. If it says "Flash Storage," you’re golden. If it says "SATA Disk," expect a slightly different experience.
Is Your Mac Actually Invited to the Party?
Apple is notorious for cutting off older models, but High Sierra was actually pretty generous. Basically, if your machine could run Sierra, it can run High Sierra.
The official roster includes:
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- MacBook (Late 2009 or newer)
- MacBook Air (Late 2010 or newer)
- MacBook Pro (Mid 2010 or newer)
- Mac mini (Mid 2010 or newer)
- iMac (Late 2009 or newer)
- Mac Pro (Mid 2010 or newer)
Don't just take my word for it. Check your RAM. If you’re trying to do this on 2GB of RAM, stop. Just don’t. You’ll hate the result. You need at least 4GB to even breathe, and 8GB if you actually want to use Chrome and Photoshop at the same time. Also, clear some space. You need about 15GB of free headers just to let the installer move things around comfortably.
The "Point of No Return" Backup
Seriously. Backup.
I’ve seen too many people try to upgrade macOS Sierra to High Sierra only to have a power flicker turn their Mac into a very expensive paperweight. Because High Sierra often converts your drive to APFS, you can’t easily "undo" the update. If something goes sideways during that file system conversion, your data is in limbo.
Use Time Machine. Or, if you want to be extra safe, use something like Carbon Copy Cloner to make a bootable clone of your Sierra drive. If the High Sierra install fails, you can just plug in your external drive, boot from it, and you're back at work in five minutes.
Finding the Installer (The Hardest Part)
Here is where it gets annoying. If you open the Mac App Store right now and search for "High Sierra," you might not see it. Apple likes to hide old versions of macOS to "encourage" you to download the newest version your Mac can handle (like Monterey or Ventura).
But your Mac might not support those.
To get the legitimate High Sierra installer, you usually have to go through a direct link on Apple’s support page which opens a hidden portal in the App Store. Don't go downloading "macOS_High_Sierra.dmg" from some random torrent site or a "free software" blog. Those are prime real estate for malware. Always get it from the source.
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The Step-by-Step Flow
- Verify your disk health. Open Disk Utility and run "First Aid" on your current Sierra drive. If there are errors now, the update will fail later.
- Plug in your power cable. Do not try this on battery. I don't care if your battery is at 100%.
- Launch the installer. It will sit in your Applications folder as "Install macOS High Sierra."
- The Conversion. During the process, your screen will go black. It will restart. It might look like it's stuck at "13 minutes remaining" for an hour. Leave it alone. ## What Happens to Your Apps?
High Sierra was the beginning of the end for 32-bit apps. While it still supports them, it’s the last version that does so comfortably. If you rely on ancient versions of Microsoft Office (like 2011) or old Adobe Creative Suite packages, you might see some "not optimized for your Mac" warnings.
Most stuff works fine. But if you’re a professional using niche audio plugins or specialized CAD software, check the compatibility forums first. High Sierra introduced Metal 2, which changed how graphics are handled. It makes the UI feel snappy, but it can occasionally trip up older, unpatched software.
Common Roadblocks and How to Smash Them
"The installer resources were not found."
Ugh. This error is the bane of the High Sierra update. Usually, it's caused by a system clock mismatch. If your Mac’s internal clock doesn't perfectly match Apple's servers, the security certificate for the installer will be rejected.
You can actually fix this by opening Terminal during the installation process and manual resetting the date using the date command. It feels like hacking into the mainframe, but it’s a common fix for older Mac updates.
Another big one: "The disk is not using the GUID Partition Table scheme." This usually happens if you’ve messed with Linux partitions or Windows Boot Camp in the past. If you see this, you’re looking at a "wipe and reinstall" situation rather than a simple upgrade.
Security and the Modern Web
Why bother with all this?
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Security. Sierra is no longer receiving security patches. This means vulnerabilities like Spectre or Meltdown, which affected almost all Intel processors, aren't fully patched on your machine. High Sierra at least gets you a few steps closer to a secure environment.
More importantly: Web Browsers. Chrome and Firefox have dropped support for Sierra. You’ll find yourself unable to log into your bank or use Gmail properly because your browser can't update to the latest security standards. Upgrading to High Sierra buys you a bit more time. It allows you to run newer versions of these browsers, keeping you functional in a world that’s moving toward 2026 standards.
HEVC and Photography
If you're an iPhone user, this upgrade is a must. High Sierra introduced support for High Efficiency Video Encoding (HEVC) and High Efficiency Image File Format (HEIF). This is the tech that lets your iPhone take high-quality photos and videos that take up half the space. On Sierra, these files often won't open or will look like corrupted junk. High Sierra handles them natively.
Making the Move
Transitioning is usually smooth. But "usually" isn't "always."
If you're worried about the APFS conversion, you can actually script the installer to skip it, but I wouldn't recommend it. Embrace the change. The speed boost on an SSD is worth the 45 minutes of staring at a loading bar.
Once you’re in, don't forget to run the App Store updates immediately. There were several "supplemental updates" released for High Sierra that fixed critical bugs discovered shortly after its 2017 launch. You want to be on the very last version (10.13.6) to ensure the best stability.
Actionable Next Steps
Check your hardware right now. Go to the Apple menu > About This Mac. If you see "macOS Sierra" and your Mac is from 2010 or later, you're a candidate.
First, grab an external drive and run a Time Machine backup. Don't skip this. Second, go to the Apple Support website to find the direct App Store link for High Sierra. Third, clear out your "Downloads" folder and trash any old apps you don't use to make space.
If you run into the "Path not found" error, don't panic. Check your internet connection, ensure your date/time settings are set to "Automatic," and try the installer again. This is a solid, stable OS that will breathe new life into an aging machine. It’s worth the effort.