Today, Microsoft released Windows 10 version 20H2 to seekers, but it's also got some cumulative update previews on the way. Specifically, the two updates are for Windows 10 versions 1909, 1903, and 1809. As is typically the case on updates that arrive outside of Patch Tuesday, these updates are optional.

If you're on Windows 10 version 1909 or 1903, you're going to get KB4580386, bringing the build number to 18363.1171 or 18362.1171, respectively. You can manually download it here, and these are the highlights:

  • Introducing Meet Now in the Windows 10 Taskbar
  • Earlier this year we introduced Meet Now in Skype. Meet Now makes it easy to connect with anyone in as little as two clicks for free and each call can last up to 24 hours. Today, we’re excited to share that we will be extending this capability in Windows 10 by bringing Meet Now right to the taskbar. In the coming weeks, you will be able to easily set up a video call and reach friends and family in an instant by clicking the Meet Now icon in the taskbar notification area. No sign ups or downloads needed.
  • Updates an issue that might prevent a Microsoft Xbox Game Pass user from playing certain games that are eligible for play.
  • Updates a reliability issue that causes the screen to flash constantly.
  • Updates an issue that causes a USB printer port to disappear after restarting when the printer device is turned power off.

As you can see, it adds the new Meet Now feature in the taskbar, which Microsoft promised would come to older versions of the OS. Here's the full list of features:

  • Addresses an issue with using Group Policy Preferences to configure the homepage in Internet Explorer.
  • Allows administrators to use a Group Policy to enable Save Target As for users in Microsoft Edge IE Mode.
  • Addresses an issue with untrusted URL navigations from Internet Explorer 11 by opening them in Microsoft Defender Application Guard using Microsoft Edge.
  • Addresses an issue that occurs when using the full suite of developer tools in Microsoft Edge for remote debugging on a Windows 10 device.
  • Addresses an issue that displays a black screen to Windows Virtual Desktop (WVD) users when they attempt to sign in.
  • Addresses an issue that might prevent a Microsoft Xbox Game Pass user from playing certain games that are eligible for play.
  • Addresses an issue that displays nothing on the screen for five minutes or more during the Remote Desktop Protocol (RDP) session.
  • Addresses a reliability issue that causes the screen to flash constantly.
  • Addresses an issue with Dynamic Data Exchange (DDE) that causes a memory leak when multiple clients connect to the same server.
  • Addresses an issue that causes an application to stop responding temporarily, which causes extra z-order operations that affect the Window.Topmost property of a window.
  • Addresses an issue that might cause DDE apps to stop working.
  • Addresses an issue that occurs when you first sign in to an account or unlock an existing user session using Remote Desktop Services (RDS). If you enter an incorrect password, the current keyboard layout changes unexpectedly to the system default keyboard layout. This keyboard layout change might cause additional attempts to sign in to fail or lead to account lockouts in domains with low account lockout thresholds.
  • Addresses an issue with the CleanupProfiles Group Policy object (GPO). After you upgrade the operating system, when you configure the CleanupProfiles GPO, it fails to remove unused user profiles.
  • Addresses an issue that displays the incorrect CPU frequency for certain processors.
  • Addresses a performance issue that occurs when PowerShell reads the registry to check if the ScriptBlockLogging registry key is in the registry.
  • Addresses an issue that randomly changes the time offset of the time format returned by the command WMIC.exe OS Get localdatetime/ value.
  • Addresses an issue that prevents Microsoft User Experience Virtualization (UE-V) from assigning the Microsoft Outlook Signatures.
  • Addresses an issue that prevents Hybrid Azure Active Directory joined devices from updating portal information when a device name or Windows version changes.
  • Addresses an issue that causes Windows to stop working and generates error 0x17. This issue occurs when Windows Defender Device Guard is enabled and a driver is loaded with a 4K Microsoft Portable Executable (PE) header.
  • Adds a new Microsoft Event Tracing for Windows (ETW) provider named "Microsoft-Antimalware-UacScan". This ETW provider reports the details of the context for each User Account Control (UAC) request in the ETW provider manifest.
  • Addresses issue that causes a USB printer port to disappear after restarting when the printer device is turned power off.
  • Addresses an issue that causes stop error 0xd1 in msiscsi.sys. This issue occurs when moving certain arrays from one cluster node to another.
  • Addresses an issue that prevents Windows Update and Microsoft Store from connecting to peers over virtual private networks (VPN) for downloads.
  • Adds functionality that shows a preview of the features and capabilities included in an update when a new update is offered to your device. On the Windows Update page (Start > Settings > Update & Security > Windows Update), there’s an option to “See what’s in this update.”
  • Adds support for the Transport Layer Security (TLS) 1.1 and 1.2 protocols when connecting to SQL Server using the data providers in Windows Defender Application Control (WDAC).
  • Addresses an issue with SQL Server that might cause performance issues if you configure a Linked Server provider to load out-of-process.
  • Addresses an issue that might degrade Windows performance and prevent the LanmanServer service from starting when third-party software uses LanmanServer custom file system controls (FSCTL).
  • Addresses an issue with deduplication that causes long wait times on Resilient File System (ReFS) Cluster Shared Volumes (CSV).
  • Addresses an issue that might prevent some applications from behaving correctly. This occurs when you publish them as Remote Application Integrated Locally (RAIL) applications using RDS and change the docking for an AppBar window.
  • Addresses an issue with a deadlock in the Transmission Control Protocol/Internet Protocol (TCPIP) driver that causes the operating system to stop working or stop responding.
  • Addresses an issue that causes the Routing and Remote Access Service (RRAS) to stop responding for new connections. However, RRAS continues working for existing connections.
  • Addresses an issue that causes the RRAS administrator Microsoft Management Console (MMC) to stop responding randomly when you are performing administrative tasks or at startup.
  • Improves the Windows Server Storage Migration Service by:
  • Adding inventory validation.
    • Improving retransfer performance .
    • Resolving multiple issues, including reliability issues.
    • Verifying that source machines have installed the current update.

There's also one known issue:

Symptom Workaround
When updating to Windows 10, version 1903 or Windows 10, version 1909 from any previous version of Windows 10, you might receive a compatibility report dialog with "What needs your attention" at the top and the error, "Continuing with the installation of Windows will remove some optional features. You may need to add them back in Settings after the installation completes." You might receive this compatibility warning when LOCAL SYSTEM accounts are blocked in a firewall from accessing the internet via HTTP. This is caused by the Windows 10 Setup Dynamic Update (DU) being unable to download required packages.

If your device has access to HTTP blocked for LOCAL SYSTEM accounts, to mitigate this issue you can enable HTTP access for the Windows 10 Setup Dynamic Update (DU) using the LOCAL SYSTEM account. After you have allowed access, you can restart installation of the update and you should not see the warning. You can also continue by clicking the OK button or use the /compat IgnoreWarning command to ignore compatibility warnings but this might also ignore other warnings that your device might be affected by.

We are working on a resolution and will provide an update in an upcoming release.

For those on Windows 10 version 1809, which won't be supported after next month's Patch Tuesday, you'll get KB4580390, bringing the build number to 17763.1554. You can manually download it here, and these are the highlights:

  • Updates an issue with the out of box user experience on some devices that prevents an upgrade from completing. This issue occurs because the device will not allow user input on the Microsoft Software License Terms page or the Cortana page.

Here's the full list of fixes:

  • Allows administrators to use a Group Policy to enable Save Target As for users in Microsoft Edge IE Mode.
  • Addresses an issue with untrusted URL navigations from Internet Explorer 11 by opening them in Microsoft Defender Application Guard using Microsoft Edge.
  • Addresses an issue that displays a black screen to Windows Virtual Desktop (WVD) users when they attempt to sign in.
  • Addresses a reliability issue in the graphics kernel.
  • Addresses an issue with the out of box user experience on some devices that prevents an upgrade from completing. This issue occurs because the device will not allow user input on the Microsoft Software License Terms page or the Cortana page.
  • Addresses an issue that causes an application to stop responding temporarily, which causes extra z-order operations that affect the Window.Topmost property of a window.
  • Addresses an issue with the CleanupProfiles Group Policy object (GPO). After you upgrade the operating system, when you configure the CleanupProfiles GPO, it fails to remove unused user profiles.
  • Addresses an issue that fails to set the desktop wallpaper as configured by a GPO when you specify the local background as a solid color.
  • Addresses an issue that prevents you from signing in on certain servers. This occurs when you enable a Group Policy that forces the start of a computer session to be interactive.
  • Addresses an issue that occurs when you first sign in to an account or unlock an existing user session using Remote Desktop Services (RDS). If you enter an incorrect password, the current keyboard layout changes unexpectedly to the system default keyboard layout. This keyboard layout change might cause additional attempts to sign in to fail or lead to account lockouts in domains with low account lockout thresholds.
  • Addresses stop error 0xC2 in usbccgp.sys.
  • Addresses an issue that displays the incorrect CPU frequency for certain processors.
  • Addresses an issue that randomly changes the time offset of the time format returned by the command WMIC.exe OS Get localdatetime/ value.
  • Addresses an issue with Task Manager reports that show an incorrect cache value for the CPU.
  • Addresses an issue that prevents Microsoft User Experience Virtualization (UE-V) from assigning the Microsoft Outlook Signatures.
  • Addresses an issue that prevents the Smart Cards for Windows service from starting, which prevents the use of a smart card for authentication. The event log shows the error, “Server Control failed to access start event: 621”.
  • Addresses an issue that causes Windows to stop working and generates error 0x17. This issue occurs when Windows Defender Device Guard is enabled, and a driver is loaded with a 4K Microsoft Portable Executable (PE) header.
  • Adds a new Microsoft Event Tracing for Windows (ETW) provider named "Microsoft-Antimalware-UacScan". This ETW provider reports the details of the context for each User Account Control (UAC) request in the ETW provider manifest.
  • Addresses an issue that causes stop error 0xd1 in msiscsi.sys. This issue occurs when moving certain arrays from one cluster node to another.
  • Addresses an issue that prevents Windows Update and Microsoft Store from connecting to peers over virtual private networks (VPN) for downloads.
  • Addresses an issue with support for On-Behalf-Of flows (OBO) when using the Microsoft Authentication Library (MSAL).
  • Adds support for the Transport Layer Security (TLS) 1.1 and 1.2 protocols when connecting to SQL Server using the data providers in Windows Defender Application Control (WDAC).
  • Addresses an issue with SQL Server that might cause performance issues if you configure a Linked Server provider to load out-of-process.
  • Addresses an issue with cluster validation that incorrectly tests internal switches that are not being used in a cluster.
  • Addresses an issue with deduplication that causes long wait times on Resilient File System (ReFS) Cluster Shared Volumes (CSV).
  • Addresses an issue that might prevent some applications from behaving correctly. This occurs when you publish them as Remote Application Integrated Locally (RAIL) applications using RDS and change the docking for an AppBar window.
  • Addresses an issue with a deadlock in the Transmission Control Protocol/Internet Protocol (TCPIP) driver that causes the operating system to stop working or stop responding.
  • Addresses an issue that causes the Routing and Remote Access Service (RRAS) to stop responding for new connections. However, RRAS continues working for existing connections.
  • Addresses an issue that causes the RRAS administrator Microsoft Management Console (MMC) to stop responding randomly when you are performing administrative tasks or at startup.
  • Improves the Windows Server Storage Migration Service by:
  • Adding inventory validation.
    • Improving retransfer performance .
    • Resolving multiple issues, including reliability issues.
    • Verifying that source machines have installed the current update.

This one also has one known issue:

Symptom Workaround
After installing KB4493509, devices with some Asian language packs installed may receive the error, "0x800f0982 – PSFX_E_MATCHING_COMPONENT_NOT_FOUND."
  1. Uninstall and reinstall any recently added language packs. For instructions, see Manage the input and display language settings in Windows 10.
  2. Select Check for Updates and install the April 2019 Cumulative Update. For instructions, see Update Windows 10.

Note If reinstalling the language pack does not mitigate the issue, reset your PC as follows:

  1. Go to the Settings app > Recovery.
  2. Select Get Started under the Reset this PC recovery option.
  3. Select Keep my Files.

Microsoft is working on a resolution and will provide an update in an upcoming release.

As usual, you need to opt into installing these to get them. If you don't, the fixes will be bundled into next month's Patch Tuesday updates, which are mandatory.