https://www.bleepingcomputer.com/news/microsoft/microsofts-april-2019-updates-are-causing-windows-to-freeze/

Conflicts between antivirus software and the recent Microsoft April 2019 Patch Tuesday updates are causing Windows 7, Windows 8.1, Windows Server 2012, and Windows Server 2012 R2 to freeze, be unable to boot, or hang on installing updates.

According to support articles from Microsoft, Avast, and Sophos, there is a conflict between some of the recent updates and antivirus software such as Sophos Endpoint Protection and Avast for Business and CloudCare.