The Spectre and Meltdown fixes are complex and require some prerequisite work for Anti-virus vendors and other companies to update their products before the JAN-2018 Windows updates will applied.  Microsoft is blocking updates in some cases where incompatibilities have been discovered.

Well, things just got a heck lot more complicated for users of some anti-virus programs.   That’s because Microsoft has said that customers who are running certain anti-virus products will not receive its bundle of January 2018 security patches (including mitigations against the Spectre and Meltdown CPU flaws) unless their products certify that they don’t make unsupported calls into Windows kernel memory.

According to Redmond, some security products jump through some hoops to bypass the Kernel Patch Protection built into the operating system. And unfortunately, those techniques, are incompatible with Microsoft’s latest patches – and cause computers to blue screen.  So, Microsoft is demanding that anti-virus products certify that their software work with its fixes by adding a registry key every time they startup.