Microsoft releases KB4566116 patch for Windows 10 to fix unlock bugs, system crashes and more

Microsoft has pushed out a new cumulative update for Windows 10 version 1903 and 1909 (builds 18362.1049 and 18363.1049). KB4566116 is also the update that sees the company backporting WSL 2 (Windows Subsystem for Linux) to these versions of Windows.

But for many people it is the bug fixes that the update brings that are of more interest -- and this update addresses a large number of problems with Windows 10. Among the issues fixed by KB4566116 are Settings crashing, errors causing hard drives to fill up, and black screens to Windows Virtual Desktop.

See also:

• Microsoft is bringing WSL 2 to older versions of Windows 10
• Microsoft makes it harder to disable Windows Defender in Windows 10
• Microsoft has removed a useful driver updating feature from Windows 10

With this particular update, Microsoft is introducing exactly the same set of fixes and changes to both Windows 10 version 1903 and 1909. The company says that there are no known issues with KB4566116, but it is entirely possible that this will change over the coming days and weeks as more and more people install it.

Microsoft has pulled out several aspects of the update which it wants to highlight:

• Updates an issue that causes the hard drive to fill up in certain error situations.
• Updates an issue that prevents Microsoft Gaming Services from starting because of error 15612.
• Updates time zone information for the Yukon, Canada.
• Updates a visual offset issue on a touchscreen. Edits you make with a pen or finger appear in a different region than expected if the device is connected to an external monitor.
• Updates an issue that causes the Settings page to close unexpectedly, which prevents default applications from being set up properly.
• Updates an issue that prevents you from unlocking a device if you typed a space before the username when you first signed in to the device.
• Updates an issue that causes applications to take a long time to open.

The full, and fairly lengthy, changelog for KB4566116 reads as follows:

• Addresses an issue with pinned Add-ins that cause Microsoft Outlook to become unresponsive.
• Provides the ability to sync the Microsoft Edge IE Mode unidirectional session cookie when an administrator configures the session cookie.
• Addresses an issue that causes the hard drive to fill up in certain error situations.
• Addresses an issue that prevents Microsoft Gaming Services from starting because of error 15612.
• Addresses an issue that prevents Visual Basic 6.0 (VB6) applications from using ListView in MSCOMCTL.OCX after upgrading to Windows 10, version 1903 and later.
• Addresses a runtime error that causes VB6 to stop working when duplicate windows messages are sent to WindowProc().
• Addresses an issue that displays a black screen to Windows Virtual Desktop (WVD) users when they attempt to sign in.
• Updates time zone information for the Yukon, Canada.
• Addresses an issue that prevents the deletion of Notification State registries for certain apps even after the user profile is deleted.
• Addresses an issue that causes an application that uses msctf.dll to stop working, and the 0xc0000005 (Access violation) exception appears.
• Addresses a visual offset issue on a touchscreen. Edits you make with a pen or finger appear in a different area than expected if the device is connected to an external monitor.
• Addresses an issue that prevents Cortana Smart lighting from working as expected if you shut down the machine while Fast Shutdown is enabled.
• Addresses an issue that causes new child windows to flicker and appear as white squares on server devices that are configured for stark visual contrast.
• Addresses an issue that causes the Settings page to close unexpectedly, which prevents default applications from being set up properly.
• Addresses an issue with File Explorer’s preview of .msg files when Microsoft Outlook 64-bit is installed.
• Addresses an issue that causes all open Universal Windows Platform (UWP) apps to close unexpectedly. This occurs when their installer calls the Restart Manager to restart File Explorer (explorer.exe).
• Addresses an issue that prevents Windows 8.1 apps from projecting to a secondary display when those apps use the StartProjectingAsync API.
• Addresses an issue that causes user profile folder names to get excessively long, which might lead to MAX_PATH issues.
• Addresses an issue that prevents a delegated user from importing a Group Policy object (GPO) even though the user has the required privilege.
• Addresses an issue that causes the Event Viewer Microsoft Management Console (MMC) to stop working when the secondary monitor is above the primary monitor. An out of bounds exception appears.
• Addresses an issue that sends a high volume of events during a real-time session in a short period of time.
• Addresses an issue with object performance counters.
• Addresses an issue that causes an error if you open Microsoft OneDrive files on demand when User Experience Virtualization (UE-V) is enabled. To apply this solution, set the following DWORD to 1: "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\UEV\Agent\Configuration\ApplyExplorerCompatFix"
• Addresses an issue that causes the promotion of a server to a domain controller to fail. This occurs when the Local Security Authority Subsystem Service (LSASS) process is set as Protected Process Light (PPL).
• Addresses an issue in which AppLocker publisher rules might sometimes prevent applications from loading software modules; this can cause partial application failure.
• Addresses an issue that sometimes prevents AppLocker from running an application whose publisher rule allows it to run.
• Addresses an issue that generates a "Sync stopped, Can't encrypt files" error when users attempt to sync their Work Folder. This issue occurs after you configure encrypted Work Folders on the client.
• Addresses an issue that causes the CryptCATAdminCalcHashFromFileHandle() function to leak memory when it’s called. That memory is not reclaimed until the calling application closes.
• Addresses an issue that prevents you from unlocking a device if you typed a space before the username when you first signed in to the device.
• Addresses an issue that causes applications to take a long time to open.
• Addresses an issue that causes a system to stop working and generates a 7E stop code.
• Addresses classification failures caused by the wrong User Principal Name (UPN).
• Addresses an issue with a sleep system call on Glibc-2.31 or later that’s running on a Windows Subsystem for Linux 1 (WSL 1) distribution.
• Adds support for WSL 2; for more information, see WSL 2 Support is coming to Windows 10 Versions 1903 and 1909.
• Addresses an issue that might display Processor Frequency as zero (0) for certain processors.
• Addresses an issue that causes delays during shutdown when running the Microsoft Keyboard Filter Service.
• Addresses an issue that prevents a host’s virtual private network (VPN) connection from sharing with virtual machines (VM) connected to the Default Switch.
• Addresses an issue with sourcing the root domain directory partition of a global catalog from a child domain controller (DC) when promoting, unhosting, or rehosting the DC. This might cause LSASS to consume all the available memory on the child DC. This issue is specific to Active Directory forests that contain 100 or more domain controllers.
• Addresses an issue that fails to log events 4732 and 4733 for Domain-Local group membership changes in certain scenarios. This occurs when you use the "Permissive Modify" control; for example, the Active Directory (AD) PowerShell modules use this control.
• Addresses an issue that might prevent the cluster service from starting and generates the error "2245 (NERR_PasswordTooShort)". This occurs if you configure the "Minimum Password Length" Group Policy with more than 14 characters. For more information, see KB4557232.
• Addresses an issue that causes the configuration of the "Minimum Password Length" Group Policy with more than 14 characters to have no effect. For more information, see KB4557232.
• Addresses an issue that causes the loss of written data when an application opens a file and writes to the end of the file in a share folder.
• Addresses an issue with Server Message Block (SMB). This issue incorrectly logs the Microsoft-Windows-SMBClient 31013 event in the Microsoft-Windows-SMBClient/Security event log of an SMB client when an SMB server returns STATUS_USER_SESSION_DELETED. This issue occurs when SMB client users or applications open multiple SMB sessions using the same set of Transmission Control Protocol (TCP) connections on the same SMB Server. This issue most likely occurs on Remote Desktop Servers.

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