Microsoft announced that it will pause optional Windows 10 updates starting in May. The move is to prioritize security updates during the coronavirus (COVID-19) pandemic. While optional non-security updates will be paused, security updates will continue as normal.

Microsoft shared the news on Twitter and linked to a doc with more information. Microsoft explains in the doc why optional non-security updates, known as C and D releases, will be paused:

Timing for upcoming Windows optional C and D releases We have been evaluating the public health situation, and we understand this is impacting our customers. In response to these challenges we are prioritizing our focus on security updates. Starting in May 2020, we are pausing all optional non-security releases (C and D updates) for all supported versions of Windows client and server products (Windows 10, version 1909 down through Windows Server 2008 SP2). There is no change to the monthly security updates (B release – Update Tuesday); these will continue as planned to ensure business continuity and to keep our customers protected and productive.

Microsoft has had several issues with updates lately, causing a myriad of bugs. Some of those issues have been minor, but some major flaws managed to make their way into publicly released Windows 10 Updates. During the coronavirus outbreak, it's even more important that security updates go smoothly. By pausing other updates, Microsoft should be able to spend more time and resources to ensure security update stability.