April 21, 2020—KB4550944 (OS Build 17134.1456)

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.

Windows 10, version 1803 (the April 2018 Update) Home and Pro editions have reached end of service. For Windows 10 devices that are at, or within several months of reaching end of service, Windows Update will automatically initiate a feature update (with users having the ability to choose a convenient time). This keeps those devices supported and receiving the monthly updates that are critical to device security and ecosystem health.

Highlights

Updates an issue with pasting mixed content of images and text from Microsoft Word into Internet Explorer.

Improvements and fixes

This non-security update includes quality improvements. Key changes include:

Addresses an issue that occurs when a third-party application loads hidden tabs into Internet Options.
Addresses an issue with pasting mixed content of images and text from Microsoft Word into Internet Explorer.
Addresses an issue that prevents the first key stroke from being recognized correctly in the DataGridView cell.
Addresses an issue that causes an error in logman.exe. The error is, "A user account is required in order to commit the current Data collector Set properties."
Addresses an issue that prevents users from setting the REG_EXPAND_SZ keys in some automated scenarios.
Addresses an issue that causes a memory leak in the LsaIso.exe process when the server is under a heavy authentication load and Credential Guard is enabled.
Addresses an issue with running klist.exe that causes lsass.exe to stop working and generates an access violation error (0xC0000005).
Addresses an issue with merging Windows Defender Application Control policies that sometimes generates a duplicate rule ID error and causes the Merge-CIPolicy PowerShell command to fail.
Addresses an issue that prevents applications running in an Azure Active Directory environment from receiving account change notifications. This occurs when using the Web Account Manager (WAM) and the WebAccountMonitor API.
Addresses a Task Manager CPU frequency display issue that locks to the base frequency on devices equipped with certain CPUs.
Addresses an issue that prevents Microsoft Internet Information Services (IIS) management tools, such as IIS Manager, from managing an ASP.NET application that has configured SameSite cookie settings in web.config.
Addresses an issue that occurs when you try to sign in to Windows during recovery mode. The error, "No administrator accounts are available on this machine", appears.
Addresses an issue that prevents you from removing some local users from local built-in groups. For example, you cannot remove "Guest" from the "Guests" local group.
Addresses an issue that prevents certain apps from installing if they are published using a Group Policy Object.
Addresses an issue that causes Microsoft Edge to stop working if you attempt to use paste functionality on webpages when cut-and-paste functionality has been disabled using a policy and Windows Defender Application Guard is active.

If you installed earlier updates, only the new fixes contained in this package will be downloaded and installed on your device.

Known issues in this update

Microsoft is not currently aware of any issues with this update.

How to get this update

Before installing this update

Microsoft strongly recommends you install the latest servicing stack update (SSU) for your operating system before installing the latest cumulative update (LCU). SSUs improve the reliability of the update process to mitigate potential issues while installing the LCU. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

If you are using Windows Update, the latest SSU (KB4540724) will be offered to you automatically. To get the standalone package for the latest SSU, search for it in the Microsoft Update Catalog.

Install this update

Release Channel	Available	Next Step
Windows Update or Microsoft Update	Yes	Go to Settings > Update & Security > Windows Update. In the Optional updates available area, you’ll find the link to download and install the update.
Microsoft Update Catalog	Yes	To get the standalone package for this update, go to the Microsoft Update Catalog website.
Windows Server Update Services (WSUS)	No	You can import this update into WSUS manually. See the Microsoft Update Catalog for instructions.

File information

For a list of the files that are provided in this update, download the file information for cumulative update 4550944.

April 21, 2020—KB4550944 (OS Build 17134.1456)

Highlights

Improvements and fixes

Known issues in this update

How to get this update

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