Microsoft has released the KB5074105 preview cumulative update for Windows 11 systems, which includes 32 changes, including fixes for sign-in, boot, and activation issues.

KB5074105 is an optional update that delivers updates at the end of each month, allowing admins to test Windows bug fixes, new features, and improvements that will be generally available during next month's Patch Tuesday release.

However, unlike Patch Tuesday cumulative updates, monthly non-security preview updates only roll out quality improvements and do not include security fixes.

With the January 2025 optional update, Microsoft addressed a known issue that caused Explorer.exe to hang during the first login when certain apps were configured as startup apps.

It also fixed a bug that caused the system to stop responding during startup when Windows Boot Manager debugging is enabled, and another bug that triggered iSCSI boot failures with an "Inaccessible Boot Device" error.

Additionally, this month's preview update addresses an issue in which Windows license migrations could fail during upgrades because the PC couldn't register with the Windows Activation server for its digital license.

You can install KB5074105 by opening Settings, clicking on Windows Update, and then on 'Check for Updates.' Since this is an optional update, you will be prompted to install it by clicking the 'Download and install' link.

However, you can also manually install this optional cumulative update after downloading it from the Microsoft Update Catalog.

Windows 11 KB5074105 highlights

Once installed, this optional non-security preview update will update Windows 11 25H2 and 24H2 devices to builds 26200.7705 and 26100.7705, respectively.

The January 2026 preview update comes with further improvements and fixes, some of the more important ones highlighted below:

• This update expands the functionality of Cross‑Device Resume. You can continue activities from your Android phone on your PC based on the apps and services you use, including resuming Spotify playback, working in Word, Excel, or PowerPoint, or continuing a browsing session.
• Windows Hello Enhanced Sign-in Security (ESS) now supports peripheral fingerprint sensors. This update extends this more secure sign-in option beyond devices with built-in fingerprint sensors to include desktops and other Windows 11 PCs, including Copilot+ PCs.
• [User Account Control (UAC)] Fixed: This update addresses an issue where your PC might stop responding when attempting to run Windows Terminal elevated from a non-admin account.
• [Graphics] Fixed: This update addresses an issue where certain GPU configurations might have recently experienced a system error related to dxgmms2.sys, resulting in the KERNEL_SECURITY_CHECK_FAILURE error.
• [Windows Sandbox] Fixed: This update addresses an issue that could cause Windows Sandbox to stop responding during startup and display error 0x800705b4.

In a separate message center update, Microsoft added that Windows 11 and Windows Server 2025 updates will get separate identifiers to avoid confusion.

"Starting with the January 2026 security update, Windows Server 2025 has its own KB identifiers and build numbers, separate from Windows 11, versions 24H2 and 25H2," Microsoft said. "This change improves clarity for administrators. Installation and management processes remain the same."

Starting this month, Microsoft has also adopted simplified titles for Windows updates, making update information easier to understand by removing unnecessary technical elements such as platform architecture.