Microsoft making sure you know why old unsupported CPU can't bypass Windows 11 requirements

Windows 11 logo with a processor on the background

Microsoft released a major Insider build earlier this week on the Dev and Canary channels. The new build, 26052, introduced several features like "Sudo for Windows," an improved Registry editor, among other things.

It also is the first Windows 11 version 24H2 build, and interestingly, it looks like Microsoft is making a fairly major change in terms of CPU instruction set architecture (ISA) support on next-gen Windows 11. The company is seemingly looking to make the SSE4's "POPCNT" instruction a mandatory requirement for running Windows 11. When a user tried to boot into Windows 11 24H2 on a system powered by such a chip, the machine failed to boot up.

Hence, it looks like users running such old processors would no longer be able to bypass Windows 11 24H2 system requirements. However, that does not mean bypass will not work on other more modern CPUs that are not on the list of supported chips. An unofficial WinPE (Windows Preinstallation Environment) tool based on build 26052 has already confirmed it will work.

While the first 24H2 build already showed that things are about to change for such users who are running really old PCs, the one after, released yesterday, is adding another change which further seems to confirm the need for the POPCNT CPU instruction.

When trying to install Windows 11 build 26058, the Setup file apparently throws up a message that says "This PC's processor doesn't support a critical feature (PopCnt)", as noticed by Twitter (now X) user Bob Pony:

Windows 11 24H2 setup blocked due to missing PopCnt instruction

This error is similar to when a Windows setup, in the past, would check if NX bit (Never eXecute), PAE (Physical Address Extension) were enabled or not, or if the SSE2 instruction was present, failing which the upgrade would be blocked.

Thankfully, there were ways to work around those blocks but it remains to be seen what happens this time. Hence, something like the Intel Core 2 Quad, like the one in the screenshot above, which is ~~perfectly capable~~ quite capable of running a basic Windows 11 PC, would be left unserviced.

Google of course has this entire situation on its radar which is why it wants owners of unsupported PCs to dump Windows 10 and 11 and switch over to its ChromeOS Flex.