KB4100347: It's no secret that some of the updates available to Microsoft cause more damage than good. A "new" security update for Specter belongs to the above update category.
We are talking about KB4100347 released Microsoft in July 2018, for repairs to the Spectre Variant 2 security slot. According to reports, some computers are no longer able to start after installing the update.
Despite the initial release two months ago, the update was re-released last week on several devices. But because KB's description page has not been updated since July, we can not say for sure whether this new version brings any changes or not.
The "new version" of KB4100347 is said to not allow some systems to boot and so far there is no solution other than removing the update.
Microsoft has not mentioned anything about the fact, so we cannot know the possible causes of these problems. The KB4100347 update "must" be installed on Intel systems, and some with AMD processors. But with both processors, there seems to be the same problem.