April 14, 2020—KB4549951 (OS Builds 18362.778 and 18363.778) - EXPIRED

^{NEW 8/5/21}
EXPIRATION NOTICE

IMPORTANT As of 8/5/2021, this KB is no longer available from Windows Update, the Microsoft Update Catalog, or other release channels.  We recommend that you update your devices to the latest security quality update. 

^NEW
IMPORTANT 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 the supported versions of Windows client and server products (Windows 10, version 1909 down to 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.

What's new for Windows 10, version 1909 and Windows 10, version 1903 release notes

Windows 10, versions 1903 and 1909 share a common core operating system and an identical set of system files. As a result, the new features in Windows 10, version 1909 were included in the recent monthly quality update for Windows 10, version 1903 (released October 8, 2019), but are currently in a dormant state. These new features will remain dormant until they are turned on using an enablement package, which is a small, quick-to-install “master switch” that simply activates the Windows 10, version 1909 features.

To reflect this change, the release notes for Windows 10, version 1903 and Windows 10, version 1909 will share an update history page. Each release page will contain a list of addressed issues for both 1903 and 1909 versions. Note that the 1909 version will always contain the fixes for 1903; however, 1903 will not contain the fixes for 1909. This page will provide you with the build numbers for both 1909 and 1903 versions so that it will be easier for support to assist you if you encounter issues.

For more details about the enablement package and how to get the feature update, see the Windows 10, version 1909 delivery options blog.

For more information about the various types of Windows updates, such as critical, security, driver, service packs, and so on, please see the following article.

Note Follow @WindowsUpdate to find out when new content is published to the release information dashboard.