Windows Secure Boot certificate expiration
Important Secure Boot certificates used by most Windows devices started to expire in June 2026. Microsoft has been updating these certificates on PCs and non-managed business devices for the past months. Devices that haven’t received the newer certificates will continue to start, and standard Windows updates will continue to install. We will continue to install the newer certificates via Windows updates in the coming months.
Summary
This article lists the security issues and quality improvements included in this cumulative security update.
Applies to: Windows Server 2019
This security update includes fixes and quality improvements that are part of the following update:
The following is a summary of the issues that this update addresses when you install this update. The bold text within the brackets indicates the item or area of the change we are documenting.
- [Backup] File History automatic backups to network shares using Server Message Block (SMB) might fail with an incorrect "invalid credentials" error. When this issue occurs, scheduled backups do not copy any files. This update resolves the issue.
- [Secure Boot] This update includes additional high confidence device targeting data, increasing coverage of devices eligible to automatically receive new Secure Boot certificates. Certificate deployment via Windows updates continues across supported PCs and non-managed business devices in the coming months.
If you installed earlier updates, only the new updates contained in this package will be downloaded and installed on your device.
For more information about security vulnerabilities, see the Security Update Guide and August 2026 Security Updates.
For information about Windows update terminology, see types of Windows updates and monthly quality update types. For an overview of Windows Server 2019, see its update history page.
Known issues in this update
We are currently not aware of any issues with this update.
Servicing stack update (KB5104020) - 17763.9015
Microsoft now combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). SSUs improves the reliability of the update process and includes fixes to the servicing stack, the component that installs Windows updates.
This servicing stack update (SSU) includes enhanced logic to verify whether a device is hosted on Azure, leveraging an updated certificate chain for validation. To ensure that the device can access the required certificate update domains to successfully download and install certificate updates, see Certificate downloads and revocation lists and Azure Certificate Authority details. To learn more about SSUs, see Servicing stack updates.
How to get this update
Before you install this update
You must have installed the August 10, 2021 SSU KB5005112 before installing this cumulative update.
Deployment
If you deploy dynamic updates such as this update to an existing Windows image, ensure the boot.stl file is included as part of the installation media. Failure to include the file might prevent devices from successfully starting from the installation media and can result in error code 0xc0430001.
Note
The boot.stl file is used during Secure Boot validation and must match the Windows version and architecture of the image you are updating.
To ensure the boot.stl file is included as part of the installation media, do one of the following:
- Use the Update WinPE script to update an existing Windows image. (Recommended)
- Manually copy the boot.stl file from the devices Windows\Boot\EFI folder to the corresponding folder on your installation media before deploying the update.
For information about how to apply Dynamic Update packages to existing Windows images, see Update Windows installation media with Dynamic Update.
Get and install this update
To get and install this update, use one of the following Windows or Microsoft release channels.
| Available | Next Step |
|---|---|
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This update will be downloaded and installed automatically from Windows Update. |
File information
A list of the files that are included in this update are provided in a CSV (Comma delimited) (*.csv) file. The file can be opened in a text editor such as Notepad or in Microsoft Excel.
Note The English (United States) version of this software update might contain files for additional languages.
Download the file information for this cumulative update KB5120238.
Download the file information for the SSU (KB5104020) - version 17763.9015 update.
Related topics
Microsoft Store application updates
Windows updates do not install Microsoft Store application updates. If you are an enterprise user, see Microsoft Store apps - Configuration Manager. If you are a consumer user, see Get updates for apps and games in Microsoft Store.Windows Secure Boot certificate expiration
Important: Secure Boot certificates used by most Windows devices have started expiring in June 2026. This might affect the ability of certain personal and business devices to boot securely if not updated in time. To avoid disruption, we recommend reviewing the guidance and taking action to update certificates in advance. For details and preparation steps, see Windows Secure Boot certificate expiration and CA updates.End of support
Microsoft will no longer provide free software updates from Windows Update, technical assistance, or security fixes on the following end dates. We recommend that you upgrade to a later version of Windows Server.
- Windows 10 Enterprise LTSC 2019: January 9, 2029
- Windows Server 2019: January 9, 2029