How to Downgrade macOS on a New Mac

For those who have recently purchased a new Mac and find themselves dissatisfied with the latest macOS version, the process of reverting to a previous operating system is a common inquiry. While Apple’s hardware, like the new M4 MacBook Air, often receives well-deserved praise, the accompanying software updates don’t always resonate with every user. The transition to macOS 26 Tahoe and its Liquid Glass interface has proven particularly polarizing, prompting a significant number of long-time Mac enthusiasts to seek a return to the more familiar environment of macOS 15 Sequoia. Fortunately, downgrading is typically possible, though it requires careful preparation and a clear understanding of the steps involved.

It’s crucial to begin with an important note about security. Apple’s update policy for macOS differs from its approach with iOS. For iPhones and iPads, if a device is capable of running the latest iOS or iPadOS version, Apple eventually mandates that update to continue receiving vital security patches. The Mac ecosystem operates differently. You can often run an older, still-supported version of macOS and continue to get security updates for that specific release, provided it remains within Apple’s support window. This flexibility is key for users who prioritize stability and a known interface over the latest features.

The downgrade process itself is not a simple one-click affair. Apple’s official guidance is spread across multiple support documents, which can be confusing to navigate. The essential first step is to ensure you have a complete, bootable backup of your current system. Using Time Machine is the most straightforward method for this. Creating a full backup before proceeding is non-negotiable, as the downgrade will erase all data on your Mac’s internal drive. This backup serves as your safety net, allowing you to restore your files and settings after the installation of the older OS.

Next, you must obtain the installer for the version of macOS you wish to install. For recent versions like Sequoia, this can usually be downloaded from the App Store if you have previously downloaded it, or found via Apple’s support pages. For older versions no longer listed, you may need to rely on archived installers from trusted sources. Once the installer is on a separate drive, you’ll need to create a bootable USB installer. This involves using the `createinstallmedia` command in Terminal, a process that requires careful attention to detail to ensure the USB drive is correctly formatted and the command is executed properly.

With the bootable installer ready, you then restart your Mac while holding down the Option key to access the Startup Manager. From there, you select the USB drive to boot from. This launches the macOS installer from the external media. The crucial step here is to use Disk Utility from the installer’s utilities menu to completely erase your Mac’s internal storage. You must select the correct disk, usually named “Macintosh HD,” and choose the APFS format before proceeding with the installation. After the erase is complete, you can exit Disk Utility and run the installer, which will then install the older macOS version onto the freshly formatted drive.

After the installation finishes and your Mac reboots into the older macOS, you will be guided through the standard setup process. At the appropriate stage, you can choose to migrate your data and applications from the Time Machine backup you created at the start. It’s wise to be selective during this migration; avoid bringing over system files or applications that might be incompatible with the older OS. Instead, focus on restoring your personal documents, photos, and essential data. Following this, you should check for any available software updates for your newly installed older macOS to ensure you have the latest security patches and bug fixes for that specific version.

While this process is methodical, it effectively returns your Mac to a previous software state. It empowers users who are unhappy with a new design language or experiencing compatibility issues to take control of their computing environment. The ability to step back provides a valuable option in an ecosystem that often emphasizes constant forward movement, ensuring that your Mac works in a way that best suits your needs and preferences.

(Source: Ars Technica)