April 9, 2019—KB4493509 (OS Build 17763.437)

Applies to: Windows 10, version 1809Windows Server 2019, all versions

Improvements and fixes


This update includes quality improvements. Key changes include:

  • Addresses an issue that occurs when you enable per font end-user-defined characters (EUDC). The system will stop working and a blue screen will appear at startup. This is not a common setting in non-Asian regions.
  • Addresses an issue that may cause applications that use MSXML6 to stop responding if an exception was thrown during node operations.
  • Addresses an issue that causes the Group Policy editor to stop responding when editing a Group Policy Object (GPO) that contains Group Policy Preferences (GPP) for Internet Explorer 10 Internet settings.
  • Addresses an issue that may cause authentication issues for Internet Explorer 11 and other applications that use WININET.DLL. This occurs when two or more people use the same user account for multiple, concurrent login sessions on the same Windows Server machine, including Remote Desktop Protocol (RDP) and Terminal Server logons.
  • Addresses an issue that may cause compound document (OLE) server applications to display embedded objects incorrectly if you use the PatBlt API to place embedded objects into the Windows Metafile (WMF).
  • Security updates to Windows Datacenter Networking, Windows Server, the Microsoft JET Database Engine, Windows Kernel, Windows Input and Composition, Microsoft Scripting Engine, Windows App Platform and Frameworks, Windows Storage and Filesystems, Microsoft Graphics Component, Windows Virtualization, Windows MSXML, Windows SQL components, and Microsoft Edge.
  • Addresses an issue with a speech subsystem in Microsoft HoloLens that causes applications to stop responding when there is no Internet connection.
  • Addresses an issue about using provisioning packages to join Azure Active Directory (AAD) domains in bulk when first setting up Microsoft HoloLens.
  • Addresses an issue about application installation notifications on Microsoft HoloLens devices.
  • Addresses an issue about the installation of sideloaded Universal Windows Platform (UWP) apps from Windows Device Portal on Microsoft HoloLens. Sideloaded means the apps are not published in the Microsoft Store.
  • Improves the efficiency of the environment data that Microsoft Azure Spatial Anchors use, which allows you to place spatial anchors in smaller physical locations in Microsoft HoloLens.
  • Addresses an issue that prevents Microsoft HoloLens from connecting to some Windows 10 mobile hotspots.

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

For more information about the resolved security vulnerabilities, please refer to the Security Update Guide.

Known issues in this update


Symptom Workaround
After installing this update, Custom URI Schemes for Application Protocol handlers may not start the corresponding application for local intranet and trusted sites on Internet Explorer.

This issue is resolved in KB4495667.

After installing this update, there may be issues using the Preboot Execution Environment (PXE) to start a device from a Windows Deployment Services (WDS) server configured to use Variable Window Extension. This may cause the connection to the WDS server to terminate prematurely while downloading the image. This issue does not affect clients or devices that are not using Variable Window Extension.

This issue is resolved in KB4503327.

Microsoft and ArcaBit have identified an issue on devices with ArcaBit antivirus software installed that may cause the system to become unresponsive upon restart after installing this update.

This issue has been resolved. Arcabit has confirmed this issue is not applicable to Window 10, version 1809.

Certain operations, such as rename, that you perform on files or folders that are on a Cluster Shared Volume (CSV) may fail with the error, “STATUS_BAD_IMPERSONATION_LEVEL (0xC00000A5)”. This occurs when you perform the operation on a CSV owner node from a process that doesn’t have administrator privilege.

Do one of the following:

  • Perform the operation from a process that has administrator privilege.
  • Perform the operation from a node that doesn’t have CSV ownership.
Microsoft is working on a resolution and will provide an update in an upcoming release.
When attempting to print from Microsoft Edge or other Universal Windows Platform (UWP) applications you may receive the error, "Your printer has experienced an unexpected configuration problem. 0x80070007e."

This issue is resolved in KB4501371.

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.

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 and applying Microsoft security fixes. For more information, see Servicing stack updates.

If you are using Windows Update, the latest SSU (KB4493510) will be offered to you automatically. To get the standalone package for the latest SSU, go to the Microsoft Update Catalog.

Install this update

This update will be downloaded and installed automatically from Windows Update. To get the standalone package for this update, go to the Microsoft Update Catalog website.

File information

For a list of the files that are provided in this update, download the file information for cumulative update 4493509

Related info