macOS Sierra USB Installer Developer Preview

If you are looking for the macOS Sierra USB installer developer preview, the short answer is that Apple released developer previews of macOS Sierra (version 10.12) starting in June 2016, and you could create a bootable USB installer from those preview builds using the same createinstallmedia method that works for final releases. This article explains what the developer preview was, how to obtain it, how to make a bootable USB drive, and what to watch out for.

Background: What Was the macOS Sierra Developer Preview?

Apple’s developer preview program gives registered developers early access to upcoming operating system versions. For macOS Sierra (10.12), the first developer preview was released at WWDC in June 2016, followed by several beta updates until the public release in September 2016. The developer preview was distributed through the Mac App Store to accounts enrolled in the Apple Developer Program. It was also possible for non-developers to install a public beta later that summer, but the developer preview specifically required a developer account.

The developer preview builds were intended for testing apps and hardware compatibility, not for everyday use. They often had bugs, missing features, and performance issues. Creating a bootable USB installer from a developer preview allowed developers to install the beta on multiple Macs without re-downloading the full installer each time.

How to Get the macOS Sierra Developer Preview Installer

To obtain the installer, you had to be enrolled in the Apple Developer Program (paid or, in some cases, free for registered developers). The steps were:

Go to developer.apple.com and sign in with your developer account.
Navigate to the Downloads section and find the macOS Sierra developer preview.
Download the installer app, typically named Install macOS Sierra.app or Install macOS 10.12 Developer Preview.app.
Keep the installer in your /Applications folder – you need it to create the USB drive.

Apple often removed older beta versions from the developer portal once newer ones were released, so if you wanted to keep a specific build, you had to save the installer before it was pulled. Some third-party sites archived these installers, but downloading from unofficial sources is risky and not recommended.

Creating a Bootable USB Installer from the Developer Preview

Once you had the installer app, the process was identical to creating a bootable USB for the final release. You needed a USB drive (at least 8 GB, but 16 GB was safer) and a Mac running macOS. Here’s how to do it using the built-in createinstallmedia tool:

Connect the USB drive and open Disk Utility (/Applications/Utilities/Disk Utility.app).
Erase the USB drive with the name MyVolume (or any name you like), using Mac OS Extended (Journaled) format and GUID Partition Map scheme.
Open Terminal (/Applications/Utilities/Terminal.app).
Run the following command, replacing MyVolume with your USB drive’s name and the path to the installer if it’s not in /Applications:

sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ Sierra.app --nointeraction

This command erases the USB drive and copies the installer files. It takes several minutes. After it finishes, you have a bootable USB installer for that specific developer preview build.

Why Use a USB Installer for a Developer Preview?

There are several reasons a developer might want a bootable USB installer:

Multiple installs: You can install the beta on several Macs without re-downloading the 5–6 GB installer each time.
Clean installs: A USB installer lets you erase the startup disk and install from scratch, which is often more reliable than upgrading over an existing system.
Testing on different hardware: Developers could test the beta on different Mac models without needing to keep the installer on each machine.
Recovery: If a beta caused problems, a USB installer could be used to reinstall the current stable macOS or the beta again.

However, Apple did not officially support creating bootable USB drives from developer previews – the createinstallmedia tool was present in the installer, but it was not documented for beta use. It generally worked, but there were occasional issues if the installer was incomplete or the USB drive was not properly formatted.

Common Problems and Troubleshooting

Creating a USB installer from a developer preview sometimes ran into issues. Here are a few common ones and how to fix them:

“createinstallmedia” not found: Make sure the installer app is in /Applications and that you’re using the correct path. If the app is named differently, adjust the command.
USB drive not showing up: Ensure the USB drive is formatted as Mac OS Extended (Journaled) and has a GUID Partition Map. If Disk Utility doesn’t show it, try a different USB port or drive.
Error “The volume is not recognized”: This usually means the USB drive was not erased properly. Re-erase it and try again.
Installer fails to boot: If the Mac doesn’t recognize the USB drive as a bootable volume, try holding the Option key during startup and selecting the drive. If it still fails, the USB drive may be too slow or defective.
Beta expires: Developer previews had an expiration date. After that date, the installer would refuse to install. You would need to download a newer beta or the final release.

If you were not a developer, you could still get the public beta later that summer, which was more stable and did not require a developer account.

Developer Preview vs. Public Beta vs. Final Release

It’s important to understand the differences:

Developer Preview: Released first, aimed at developers, often unstable, and required a developer account.
Public Beta: Released a few weeks later, more polished, available to anyone through the Apple Beta Software Program.
Final Release: The stable version released to all Mac users in September 2016.

For most people, the public beta or final release was a better choice. The developer preview was specifically for testing and development, not for daily use. If you just wanted to try Sierra early, the public beta was the safer option.

Safety and Legitimacy Concerns

Downloading developer previews from unofficial sources is risky. These files could be tampered with, contain malware, or simply not work. Apple’s developer previews were only distributed through the official developer portal. If you did not have a developer account, you should not try to obtain the developer preview from third-party sites. Instead, wait for the public beta or the final release.

Also, installing a developer preview on a primary machine could lead to data loss or hardware issues. It was recommended to install it on a separate partition or a test Mac, and always back up your data first.

Alternatives to a USB Installer

If you didn’t need a bootable USB drive, you could simply run the installer app directly from /Applications. That would upgrade your current macOS to the beta version. However, that method didn’t allow a clean install and was harder to use for multiple machines.

Another option was to use a virtual machine (like VirtualBox or VMware) to run the beta without affecting your main system. That was useful for testing apps without dedicating a physical Mac.

Frequently Asked Questions

Can I still download the macOS Sierra developer preview?
No, Apple no longer distributes the Sierra developer previews. The final version of macOS Sierra is also no longer available from the Mac App Store (as of 2023), though you might find it through other means, but that is not recommended.

Do I need a developer account to create a USB installer from the developer preview?
Yes, you needed a developer account to download the developer preview installer. Without it, you could not legally obtain the developer preview.

Will the USB installer work on any Mac?
The macOS Sierra developer preview supported a specific list of Mac models. If your Mac was not on that list, the installer would not boot or install. You can check the compatibility list from Apple’s website (for the final release, it was similar).

Can I use the developer preview USB installer to install the final release?
No, the developer preview installer only installs that specific beta build. You would need to download the final release installer separately to create a USB for the final version.

Is it safe to use a developer preview on my daily Mac?
No, developer previews are unstable and not intended for production use. Always back up your data and install on a test machine or partition.

What if my USB drive is 8 GB, is that enough?
The macOS Sierra installer was about 5–6 GB, so an 8 GB USB drive was technically enough, but a 16 GB drive is more comfortable and avoids issues with slightly larger beta builds.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

More in this bed

The whole Tech How-To bed →