Testing Windows has always allowed you to try out new features ahead of time, even a new operating system. But the Windows 11 26H1 release Microsoft is testing now literally breaks Windows into two parallel tracks, separated into x86 and Arm.

Some of this isn’t new: Microsoft said last November that Windows 11 26H1 would be used to test “specific silicon,” believed to be the Snapdragon X2 Elite chips that Qualcomm debuted last fall. That’s now confirmed. Microsoft also released a new Windows 26H1 build this week, with the expectation that the majority of PC users will eventually be shunted to the Windows 11 26H2 release this fall.

But here’s the thing: Laptops with Windows 11 26H1 on them won’t be upgradable to Windows 11 26H2. They’ll remain on a separate Windows track until an undisclosed time.

In a Microsoft support document released Tuesday, Microsoft reiterated that “Windows 11, version 26H1 will only be available on new devices with select new silicon as they come to market in early 2026.” Again, that’s not entirely new, but means that devices like new iterations of the Microsoft Surface Laptop and Pro will be powered by X2 Elite chips, Windows 11 26H1, and whatever unique Windows experiences Microsoft puts on them.

This, though, is the surprise. “Devices running Windows 11, version 26H1 will not be able to update to the next annual feature update in the second half of 2026,” Microsoft added. “This is because Windows 11, version 26H1 is based on a different Windows core than Windows 11, versions 24H2 and 25H2, and the upcoming feature update. These devices will have a path to update in a future Windows release.”

This is new. You’ve always been able to test, say, Windows 11, when Windows 10 was nearing the end of its life. And when a new iteration of Windows was nearing release, you’ve often had a choice of testing the version that was just about to release, versus more experimental code designed to ship further down the roadmap. But it was always basically a single, serial path: All of the code would eventually land on your PC, if Microsoft deemed it worthy enough to roll out.

That’s not the case now. Assuming that Windows 11 26H1 is exclusive to the Snapdragon X2 Elite, Windows on Arm now has its own path forward. Windows on x86 does too. Microsoft is also telling us that this will last for longer than just six months or so, until Windows 11 26H2 releases. Both Windows 11 26H1 and H2 will receive their own patches and updates.

Referring to a “different Windows core” could simply mean that Microsoft is calling out that 26H1 runs on Arm. It doesn’t sound like it, though. We now have two parallel tracks: one for Arm, and one for x86. In coding, developers refer to that as a “fork,” with development going off in two separate directions.

That certainly seems to be what’s happening here. What’s odd about the whole situation is that I’ve been told that Microsoft feels that the PC has become a little too complicated, and that consumers are asking for simplicity. That may be why Microsoft is separating the Arm development path into its own track, so that consumers who know and understand Arm might feel comfortable trying out these new experiences. But it still adds another choice for consumers to make.

On the other hand, it also makes anything rolled out with Windows 11 26H1 onboard a sort of commercialized beta program. Do I want to buy into a taste of the future, or stick with the tried and true? How does the Windows 11 26H1 code base reconcile with the x86 path in the future? Is Windows 11 26H1 just a preview of what will eventually be Windows 12? It certainly could be. But how, and when, and who gets it are questions we didn’t have until this week.

Microsoft just split Windows into two, and things just got even more interesting.

Author: Mark Hachman, Senior Editor, PCWorld