An Ars Technica colleague recently bought a new M4 MacBook Air. I have essentially nothing bad to say about this hardware, except to point out that even in our current memory shortage apocalypse, Apple is still charging higher-than-market-rates for RAM and SSD upgrades. Still, most people buying this laptop will have a perfectly nice time with it. But for this colleague, it was also their first interaction with macOS 26 Tahoe and the Liquid Glass redesign, the Mac’s first major software design update since the Apple Silicon era began with macOS 11 Big Sur in 2020. Negative consumer reaction to Liquid Glass has been overstated by some members of the Apple enthusiast media ecosystem, and Apple’s data shows that iOS 26 adoption rates are roughly in line with those of the last few years. But the Mac’s foray into Liquid Glass has drawn particular ire from longtime users (developers Jeff Johnson and Norbert Heger have been tracking persistently weird Finder and window resizing behavior, to pick two concrete examples, and Daring Fireball’s John Gruber has encouraged users not to upgrade). My general approach to software redesigns is to just roll with them and let their imperfections and quirks become background noise over time—it’s part of my job to point out problems where I see them, but I also need to keep up with new releases whether I’m in love with them or not. But this person has no such job requirement, and they had two questions: Can I downgrade this? And if so, how? The answer to the first question is “yes, usually,” and Apple provides some advice scattered across multiple documentation pages. This is an attempt to bring all of those steps together into one page, aimed directly at new Mac buyers who are desperate to switch from Tahoe to the more-familiar macOS 15 Sequoia. Table of Contents Jump to section A preemptive warning about security updates and older versions of macOS Before we begin: Apple handles macOS updates differently from iOS updates. Eventually, Apple requires devices that support the latest iOS and iPadOS versions to install those updates if they want to continue getting security patches. That means if your iPhone or iPad can run iOS or iPadOS 26, it needs to be running iOS or iPadOS 26 to stay patched.