https://www.bleepingcomputer.com/news/microsoft/windows-10-april-2019-cumulative-updates-released-with-fixes/

Today is second Tuesday of the month and the new cumulative updates are rolling out for supported versions of Windows 10, including the October 2018 Update, the April 2018 Update and the Fall Creators Update. Microsoft has also released a cumulative update for devices running the Insider preview builds of the upcoming Windows 10 May 2019 Update.

The April 2019 patches for all versions of Windows include security or non-security fixes and improvements.