Microsoft is investigating Bluetooth issues, failures to install, and blue screen reports. KB4549951 cumulative update was released during this month’s Patch Tuesday. Users are reporting a wide assortment of issues when installing and after deploying the update. Microsoft is asking customers who have been experiencing issues related to the update to report them via the Feedback Hub. If you haven’t yet installed the update, you can follow the procedure described below to roll back the security fixes it comes with, if you are willing to remove it.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-investigating-windows-10-kb4549951-bsod-reports/