UPDATE, January 9: Microsoft confirmed the issue and pulled the update until a fix is ready. Original article below.



Microsoft rolled out Windows 10 cumulative update KB4056892 yesterday as an emergency patch for systems running the Fall Creators Update in an attempt to fix the Meltdown and Spectre bugs affecting Intel, AMD, and ARM processors manufactured in the last two decades.

But as it turns out, instead of fixing the two security vulnerabilities on some computers, the cumulative update actually breaks them down, with several users complaining that their systems were rendered useless after attempting to install KB4056892.

Our readers pointed me to three different Microsoft Community threads (1, 2, 3) where users reported cumulative update KB4056892 issues, and in every case the problem appears to be exactly the same: AMD systems end up with a boot error before trying a rollback and failing with error 0x800f0845.

Incompatible processors?

User Jaroslav Škarvada speculates that Windows 10 cumulative update KB4056892 might not be compatible with his AMD processor, and this could indeed be the case since I’ve found at least two reports of similar bugs happening on systems with Athlon 64 X2 CPUs.

“I have older AMD Athlon 64 X2 6000+, Asus MB, after installation of KB4056892 the system doesn't boot, it only shows the Windows logo without animation and nothing more,” the user explains in one of the linked discussions on the support forums.

“After several failed boots it do roll-back then it shows error 0x800f0845. Unfortunately, it seems it's not easy to disable the automatic updates without gpedit tweaks, so it tries installing and rolling-back the update over and over. The sfc /scannow shows no problem, in-place upgrade also doesn't seem to help.”

Microsoft is yet to acknowledge the problem and the official knowledge base article of the update doesn’t point to any known issue with a behavior similar to the one reported here. Also, it doesn’t seem to be related to the antivirus bug as in at least one reported case Windows Defender was the running antivirus.

It remains to be seen if Microsoft determines what causes the problem and how fast it does it, though it goes without saying the company should really hurry up since this cumulative update fixes critical security issues.

We have reached out to Microsoft to ask for more information about these issues and will update the article when an answer is offered.