Building a macOS Golden Gate bootable USB takes an Apple silicon Mac and a 32GB drive, because the full installer is 18.41GB and the drive is erased during the process.
This guide shows two separate ways to get there, macUSB or Terminal, and either one downloads the installer straight from Apple and builds the same finished drive. That drive installs macOS Golden Gate on any supported Mac without another download, and it still works when Software Update fails.
Only Apple silicon Macs can build a macOS Golden Gate bootable USB
Apple released macOS Golden Gate on September 14, and it is the first Mac release with no Intel support. Intel Macs can’t run Golden Gate at all, including the four that ran macOS Tahoe, which are the 2019 16-inch MacBook Pro, the 2020 four-port 13-inch MacBook Pro, the 2020 iMac and the 2019 Mac Pro. No patcher changes that, because the Golden Gate kernel runs only on ARM64.
The macUSB app warns Intel Mac owners before the Golden Gate download starts, because building the drive needs Apple silicon. An Intel Mac can still make installers for older releases, but the Golden Gate drive has to come from an Apple silicon Mac.
Apple supports Golden Gate on Apple silicon Macs back to the 2020 M1 models, plus the MacBook Neo. Open the Apple menu and choose About This Mac to see your chip, then compare it with the table below or the full macOS 27 compatibility list.
| Mac | Supported models |
|---|---|
| MacBook Pro | 16-inch and 14-inch with M5 Pro or M5 Max, 14-inch M5, 16-inch and 14-inch from 2024, 2023 and 2021, 13-inch M2 (2022), 13-inch M1 (2020) |
| MacBook Air | 13-inch and 15-inch M5, 13-inch and 15-inch M4 (2025), 13-inch and 15-inch M3 (2024), 15-inch M2 (2023), M2 (2022), M1 (2020) |
| MacBook Neo | 13-inch, A18 Pro |
| iMac | 24-inch (2024, four ports and two ports), 24-inch (2023, four ports and two ports), 24-inch M1 (2021) |
| Mac mini | M6 or M5 Pro, 2024, 2023, M1 (2020) |
| Mac Studio | M5 Max or M5 Ultra, 2025, 2023, 2022 |
| Mac Pro | 2023 |
Intel apps still run on Apple silicon through Rosetta in Golden Gate, which is the last macOS release with full Rosetta support. Check which Intel apps break in macOS 28 before you wipe anything.
A 32GB USB drive and a direct connection avoid most failures
A flash drive of 32GB or larger is the right size for macOS Golden Gate, because the installer is 18.41GB and a 16GB stick cannot hold it. The same 32GB drive also fits every other recent macOS installer, which makes it a safe default to keep around. A USB 3.0 or faster drive is recommended, and an external SSD works too once you switch on the external drive option in macUSB’s Options menu.
Plug the drive straight into the Mac instead of a hub, and copy off anything you want to keep, because the drive is erased and formatted as Mac OS Extended (Journaled). The Mac also needs an internet connection when it boots from the drive, since the installer pulls firmware and model-specific information.
Back up the Mac you plan to upgrade before you touch it. If your backups go to a Time Capsule, Time Capsule support ended in Golden Gate when Apple removed AFP, so you need another backup drive first.
Two methods to build a macOS Golden Gate bootable USB
A bootable drive needs the full installer app in the Applications folder. Software Update, found in System Settings under General, is the fastest way to upgrade the Mac in front of you and can use less storage than the other methods, but it does not build a drive. The two methods below are separate routes to the same finished USB, so pick one and follow only that section.
Choose macUSB if you want a visual, step-by-step app, or Terminal if you prefer built-in commands and no extra software. Both end with the same boot steps near the bottom of this guide.
1. Use macUSB to download the installer and build the drive
Method 1 needs no Terminal commands, because macUSB handles both the download and the drive. macUSB is a free, open-source app written natively in Swift, and version 2.6 needs macOS Sonoma 14.6 or newer. Golden Gate support arrived in version 2.4. Download the DMG from the site, or install it through Homebrew with the command below.
brew install --cask macusb
Before the first run, open System Settings and switch on Allow in the Background under General, Login Items & Extensions. Then add macUSB under Privacy & Security, Full Disk Access, because creation can fail without both permissions. The same app also writes Windows and Linux ISOs to USB, which makes it a single tool for other installers too.
Open macUSB and download macOS Golden Gate
Open macUSB, click Start and then click Download on the source screen to see the installers available from Apple’s servers. The Systems available section puts macOS Golden Gate 27.0 (build 26A428, 18.41GB) at the top.
The built-in downloader pulls installers straight from Apple’s servers instead of a third-party mirror, shows real-time progress and checks the exact amount of free disk room before it starts. It can also save the installer as a read-only DMG in a folder you choose.
Select it and macUSB works through connecting to Apple’s servers, downloading, verifying, preparing the installer and finalizing. The summary then shows where the installer was saved in Applications and offers to continue straight to USB creation. The progress and summary screens below show macOS Big Sur as the example installer.
If you already have an installer, click Select instead and pick an app, DMG, CDR or ISO file, then click Analyze so macUSB detects the macOS version. Calculate Checksum runs a SHA-256 check on supported images.
Plug in the 32GB drive and pick it from the target USB drive menu. The warning on this screen means every file on the drive is permanently erased, so check the drive name before you click Continue.
The operation details screen then shows what happens next, which is preparing the system files, formatting the USB drive, copying the installation files and removing temporary files automatically. Click Start when the drive and macOS version are right.
The creation screen moves through preparing installer files, preparing the USB media, creating the installation media and cleaning up temporary files. The copy step shows a live percentage and write speed, and the whole run takes several minutes. A Stop button is available, but macUSB blocks quitting the app while a build is running.
A green Success screen confirms the USB media was prepared correctly. Click Eject Drive before disconnecting the stick from the Mac. The closing screen tells you to hold Option at startup, which is the Intel method, so Apple silicon Macs use the power button instead. That finishes Method 1, and you can skip ahead to the boot steps.
2. Use Terminal commands to download the installer and build the drive
Method 2 gives the same finished drive as macUSB with no extra app, so skip this section if you already used Method 1. It needs macOS Catalina 10.15 or later and takes two stages, a download and then the build.
Download the installer with Terminal
Open Terminal from Applications and Utilities, then check which installers your Mac can download.
softwareupdate --list-full-installers
Fetch the Golden Gate installer next, replacing [version] with the Golden Gate number the first command returns. If Terminal reports that no update was found, run the first command again and use a version number it returns.
softwareupdate --fetch-full-installer --full-installer-version [version]
Wait for the download to reach 100% in Terminal, after which the installer sits in the Applications folder. If macOS opens the installer on its own, quit it before moving on to the next stage.
Build the drive with the createinstallmedia command
The command fails when the installer name differs, so check that the Applications folder holds Install macOS 27 Golden Gate before you start.
- Connect the drive and rename it to MyVolume in Finder, since the command refers to that exact name.
- Open Terminal and paste the command below, then press Return.
sudo "/Applications/Install macOS 27 Golden Gate.app/Contents/Resources/createinstallmedia" --volume /Volumes/MyVolume
- Enter your administrator password when Terminal asks for it, and expect nothing to appear on screen while you type.
- Type Y and press Return to confirm the erase, and allow Terminal to access the removable volume if macOS asks.
- Wait until Terminal reports that the install media is ready. The drive now carries the installer’s name, so quit Terminal and eject it.
Delete the installer from Applications afterward if you want the 18GB back. A drive with a different name means changing /Volumes/MyVolume in the command to match.
Apple silicon Macs boot from the USB installer through the power button
Both methods produce the same drive, so these boot steps apply whichever one you used.
- Shut down the Mac and plug the drive directly into it.
- Press and hold the power button until the startup options appear.
- Choose the installer drive and click Continue.
- Follow the onscreen instructions, keeping the Mac online.
A circle with a line through it at startup means the installer does not match that Mac. macOS Recovery on Apple silicon is the built-in fallback when you do not have the drive with you.
Fixes for the errors that stop a bootable USB build
- With Terminal, a “not a valid installer application” message means the download is damaged. Delete the installer, repair the startup disk in Disk Utility and download it again.
- With Terminal, “command not found” means the command does not match the installer. Confirm the app is in Applications with the exact name the command uses.
- With Terminal, when the erase fails, erase the drive in Disk Utility as Mac OS Extended (Journaled) and run the command again.
- With either method, a drive that reports too little capacity is too small, so switch to a 32GB drive.
- With macUSB, if the app stops at the start, recheck Allow in the Background and Full Disk Access, and confirm the Mac runs macOS Sonoma 14.6 or newer.
- With either method, when the Mac does not show the drive at startup, move it from a hub to a port on the Mac itself.
Leave room on the startup disk too, because Apple Intelligence storage use reaches 20GB to 30GB on some Macs, and you can free up storage on your Mac afterward. The first-day checks are in 10 things to do after installing macOS 27, and the common macOS 27 problems are worth a look if anything misbehaves.
Questions about downloading macOS Golden Gate and making a bootable USB
How big is the macOS Golden Gate installer?
The macUSB downloader shows macOS Golden Gate 27.0 at 18.41GB. That size is why a 32GB drive is the safe choice and a 16GB stick is too small.
Can an Intel Mac create a macOS Golden Gate bootable USB?
No. Golden Gate installers can only be built on Apple silicon Macs, and the macUSB app warns Intel Mac owners before the download starts. Intel Macs can still build drives for older macOS releases.
Do I need a bootable USB to install macOS Golden Gate?
No. Software Update upgrades a compatible Mac without one. A bootable drive helps when you install on several Macs without downloading the installer each time, or when Software Update and macOS Recovery fail.
Is macUSB free and safe to use?
The macUSB app is free and open source under the MIT license, so the code is public on GitHub. It checks the signatures of downloaded installer packages, and since version 2.3.1 the app and its helper verify each other’s code signatures before any privileged step.
Should I use macUSB or Terminal to make the bootable USB?
Either one works and the finished drive is identical. The macUSB app suits anyone who wants a guided walkthrough with a built-in downloader, while Terminal needs no extra software but depends on typing the installer name and volume name exactly.
Can macUSB make bootable drives for older versions of macOS?
Yes. It supports releases from Golden Gate back to Mac OS X Tiger 10.4, and on Apple silicon it works around the expired-certificate errors that often break older installers. For a Terminal route, we have step-by-step guides for a bootable USB for macOS Tahoe, macOS Ventura, macOS Monterey and macOS Big Sur, and you can download the Tahoe installer without the Mac App Store.
Can I use an external SSD instead of a flash drive?
Yes. Terminal accepts any secondary volume, and macUSB handles external hard drives and SSDs once you enable them in Options. That external drive option resets to off every time macUSB launches.
Which macOS versions does the macUSB downloader offer?
The downloader shows macOS Golden Gate 27.0 at 18.41GB, macOS Tahoe 26.7 at 18.39GB, macOS Sequoia 15.8 at 15.67GB, macOS Sonoma 14.8.9 at 13.67GB and macOS Ventura 13.7.8 at 12.22GB, with older releases further down.
