https://www.bleepingcomputer.com/news/microsoft/microsoft-confirms-windows-10-kb4524244-issues-and-pulls-the-update/

Microsoft pulled the standalone KB4524244 security update today, February 15, 2019, from Windows Update after confirming user reports about freezes, boot problems, and installation issues since it was released on February 11.

KB4524244 was designed to address "an issue in which a third-party Unified Extensible Firmware Interface (UEFI) boot manager might expose UEFI-enabled computers to a security vulnerability."