The unofficial patch from a developer calling him or herself ‘Zeffy’ on GitHub targets those running very new CPUs on older versions of Windows. Windows 7 and 8 are still supported with updates, but Microsoft has started blocking non-security updates for systems that run Intel 7th-Generation Kaby Lake processors, AMD “Bristol Ridge” Rizen chips, or the Qualcomm 8996 (Snapdragon 820 and 821) SoC.
If you try to install the new April patches for Windows 7 or 8.1 on these systems, it will fail with error code 8024003. The only solution Microsoft offers for that error is to upgrade to Windows 10. To be clear, there does not seem to be any legitimate reason to block these updates. Microsoft just really, really wants you to use Windows 10.
The Zeffy patch goes after a change Microsoft introduced in March that identifies the system’s CPU. As the changelog explained at the time, the patch “Enabled detection of processor generation and hardware support when PC tries to scan or download updates through Windows Update.” Zeffy is very clear on his dislike for Windows 10 when he calls this “essentially a giant middle finger to anyone who dare not ‘upgrade’ to the steaming pile of garbage known as Windows 10.”
Should you install Zeffy’s fix, two functions found in wuaueng.dll update code will be disabled. It is these functions, IsCPUSupported(void) and IsDeviceServiceable(void), that are responsible for blocking the update. This patch reportedly does the job, allowing you to install the previously blocked non-security updates on Windows 7 and 8.1 on affected systems. However, the Zeffy patch will need to be reapplied every time wuaueng.dll is updated by Microsoft. It’s also possible a future update will try to prevent this workaround. Then, maybe someone will release another custom patch, Microsoft will block that one, and then the whole thing starts all over.
The patch download is less than a megabyte and installs in a single step. The source code is available, so it’s unlikely Zeffy is up to anything shady. That said, using a third-party tool to modify Windows system files is not without risk.