You're likely here because an old MacBook is staring you in the face with a flashing folder icon. Or maybe you're trying to breathe life into a 2011 iMac that’s been gathering dust in the closet. Whatever the reason, you need a High Sierra bootable USB, and honestly, it’s getting harder to do this every year. Apple doesn’t make it easy to reach back into the past.
Modern macOS versions try to block you. Certificates expire. The App Store link for macOS 10.13 often leads to a dead end or a "Update Not Found" error. It's frustrating. But if you have an older machine that tops out at High Sierra—or if you specifically need it for its compatibility with HFS+ and older 32-bit apps—creating a physical installer is the only way to ensure you aren't stranded when the recovery partition fails.
Why High Sierra Still Matters in 2026
It feels like forever ago that Craig Federighi stood on stage and joked about "High" Sierra being the refined version of Sierra. Yet, for a specific subset of users, this OS is a lifeline. If you're running Pro Tools hardware that requires specific drivers or using a mid-2010 Mac Pro that you've upgraded with a metal-capable GPU, High Sierra is often the sweet spot.
It was the transition point. It introduced APFS (Apple File System) but still played nice with the older world. It’s also the last stop for many machines before they were officially "obsoleted." Having a High Sierra bootable USB in your desk drawer is basically an insurance policy for vintage hardware. If your hard drive dies today, you can't just "Internet Recovery" your way out of it easily anymore because the servers often reject the handshake from such old firmware.
The Stuff You Actually Need Before Starting
Don't just grab any random thumb drive. I've seen people try this with 4GB sticks they found in a junk drawer, and it fails every time. You need at least 16GB. Technically, the installer is around 5.2GB, but the way the "createinstallmedia" command handles the headers and the boot sector requires more breathing room.
- A 16GB+ USB Drive: Preferably USB 3.0, unless you enjoy watching a progress bar for two hours.
- The Installer File: This is the hard part. You need
Install macOS High Sierra.appin your Applications folder. - A Working Mac: It needs to be running an OS that can actually download the installer. If you're on a brand new M3 MacBook Pro, downloading High Sierra from the App Store is nearly impossible without using third-party scripts.
There is a common pitfall here. Sometimes the file you download is only 20MB. That's a "stub" installer. It won't work for a bootable USB. You need the full 5GB+ version. If you keep getting the tiny version, you might need to use a tool like macOS-Installer-Download or the MDS (Mac Deploy Stick) utility from Two Canoes Software. Timothy Perfitt and his team over there have saved more Mac admins than I can count with their tools for fetching legacy installers.
The Terminal Command: No Room for Error
Most people are scared of Terminal. Don't be. It’s the only reliable way to do this. Third-party "maker" apps often fail because they don't properly bless the boot partition.
First, plug in your USB. Open Disk Utility and erase it. Name it Untitled. It makes the command easier. Format it as Mac OS Extended (Journaled) and make sure the scheme is GUID Partition Map. If you don't see the scheme option, go to the "View" menu in Disk Utility and select "Show All Devices." Click the top-level external drive, not the volume underneath it.
Now, open Terminal and paste this:
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sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
It will ask for your password. You won't see dots while you type. Just hit Enter. It’ll ask if you want to erase the disk. Type Y. Then, you wait.
What if it says "Command not found"?
This usually means your installer isn't actually in the Applications folder, or it's named something weird like Install macOS High Sierra 1.app. Check the name. Fix it. Run it again.
Dealing With the "Damaged" Installer Error
This is the big one. You've spent thirty minutes making the High Sierra bootable USB, you boot from it, you click install, and then: "This copy of the Install macOS High Sierra application is damaged, and can’t be used to install macOS."
It isn't actually damaged.
Apple’s security certificates for old installers expire. The installer thinks it's "expired" because the system clock on your Mac says it's 2026, but the certificate died years ago. You have to trick the Mac into thinking it’s 2018.
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- Turn off your Wi-Fi (this is crucial, or it will auto-update the time).
- Open Terminal from the Utilities menu in the installer screen.
- Type
date 0101010118and hit Enter.
This sets the date to January 1st, 2018. Close Terminal and try the installer again. It should work perfectly now. This is a classic "gotcha" that drives people crazy, leading them to delete and re-download the installer over and over when the fix is just a simple clock change.
Hardware Compatibility Check
High Sierra is picky. It was the first OS to require a Firmware update to support APFS on SSDs. If you are installing this on a 2010 or 2012 Mac Pro, and you’re using an NVMe drive via a PCIe adapter, you must ensure your firmware is updated to version 144.0.0.0.0. Usually, the High Sierra installer handles this, but it will only do so if you have a "Metal" supported GPU like an RX 580 or the original GT 120.
If you're on a MacBook, just make sure your battery has a charge. If it dies during a firmware update while installing High Sierra, you’ve got a brick.
Actually, speaking of firmware—if you're trying to install this on a machine that currently has a newer OS, like Mojave or Catalina, the installer might act weird. It’s always best to wipe the target drive completely in Disk Utility (select the root drive, erase as APFS or HFS+) before starting the install. High Sierra will automatically convert any SSD to APFS anyway, so don't fight it.
APFS vs. HFS+: The Great Partition Debate
When High Sierra launched, it forced the world into APFS. For SSDs, this was a godsend. It handles metadata much faster and makes cloning files near-instant. But if you're installing this on a machine with a traditional spinning hard drive (an old Mac Mini or an iMac), APFS can actually make the machine feel slower.
If you really want to keep HFS+ on an SSD, there are "unsupported" ways to skip the conversion, but I wouldn't recommend it. Most of the stability improvements in later High Sierra patches (10.13.6) were built around the way APFS handles data integrity.
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Troubleshooting the Boot Process
So you’ve made the High Sierra bootable USB, but the Mac won't see it when you hold the Option (Alt) key?
Check your ports. On older Macs, sometimes the USB ports on the left side fail to initialize during the boot picker. Try the right side. If you're using a wired PC keyboard, the Windows key is usually the Option key.
Another weird quirk: If you’re using a wireless Bluetooth Apple keyboard, it might not pair fast enough to catch the boot command. Plug it in via the Lightning cable or find a cheap $5 USB keyboard to get through the initial selection screen.
Moving Forward With Your Installation
Once the progress bar finishes and you see that familiar mountain wallpaper, you aren't quite done. High Sierra is "old" by web standards. The version of Safari included with it won't load many modern websites because the security protocols are out of date.
Your first move should be to download a browser that still supports 10.13, like Legacy-Firefox or the Chromium Legacy project. This allows you to actually use the internet without getting a thousand "Your connection is not private" errors.
Essential Next Steps
- Security Updates: Go to the App Store and grab the 2020-006 High Sierra security update. It’s the last one ever released.
- Web Drivers: If you’re on a Mac Pro with an NVIDIA card, you’ll need the specific "Web Drivers" for your build number. High Sierra was the very last macOS to support these.
- Backup your USB: Don't erase that thumb drive. Label it "High Sierra" and put it in a safe spot. As Apple's servers get older, these installers become harder to find.
If you follow these steps, you'll have a rock-solid system. High Sierra might not be the newest kid on the block, but for reviving older hardware or maintaining a specific creative workflow, it remains a vital piece of the macOS timeline. Just remember that date trick in the Terminal—it’s the difference between a successful afternoon and a weekend of frustration.