KB5074178

Microsoft has released cumulative update KB5074178 for Windows 11 version 25H2 for insiders in the Dev Channel – this is a Windows 11 Insider Preview quality update (26300.7733). Windows 11 Insider Preview Build 26300.7733 (KB5074178) has been released.

Users in this channel will now receive updates for Windows 11 version 25H2, which are provided via the enablement package KB5073032 (build 26300.xxx). The Dev Channel includes the latest Windows 11 preview builds with new features. These builds may have lower stability and some issues, but they are intended for enthusiasts who want to try new operating system features in advance.

• Built-in Sysmon support. Microsoft is integrating Sysmon directly into Windows 11 and Windows Server 2025. The Dev Channel now has built-in Sysmon support – a system monitoring tool previously available separately as part of the Sysinternals suite. Sysmon functionality is now integrated directly into the operating system. Sysmon allows logging of system events useful for threat detection and security analysis, and also allows custom configuration files to filter tracked events. All collected data is written to the Windows Event Log, making it easier to use in security tools and analysis scripts.
• Voice Access support for Dutch. Added support for the Netherlands (Dutch) language for the Voice Access feature, expanding the list of supported locales and improving the accessibility of hands-free voice control in Windows.
• Fix for application freezes when working with cloud files. Fixed an issue that could cause applications to freeze when working with files stored in cloud services such as OneDrive or Dropbox. In some configurations, Outlook with PST files hosted in OneDrive could freeze or repeatedly reload mail data.

Updates for Windows insiders in the Dev Channel are delivered based on Windows 11 version 25H2 via the enablement package (builds 26300.xxxx).

Installation via Windows Update: go to Settings > Windows Update and click Check for updates. A computer restart is required to complete installation.

Note: If Sysmon was previously installed manually from the Sysinternals website, it must be removed before enabling the built-in version. The core functionality of Sysmon remains unchanged.

How the new features work:

Built-in Sysmon support: In Windows 11 and Server 2025, Sysmon is integrated directly into the OS kernel. It operates as a driver and service hooking system calls (process creation, network connections, file changes). Events are written to the Microsoft-Windows-Sysmon/Operational event log. You can load an XML configuration via registry or command line – Sysmon filters events before writing them, reducing noise.

Voice Access support for Dutch: Voice Access now supports Dutch (Netherlands) language. This extends acoustic and language models – adding Dutch phonemes, lexicon, and grammar. Voice commands, dictation, and text correction run locally (no cloud) using the Windows Speech Platform engine.

Fix for application freezes when working with cloud files: Fixed app freezes (e.g., Outlook) with cloud files (OneDrive, Dropbox). The bug was caused by the cloud files filter (CfAPI) and sync engine mishandling opportunistic locks (oplocks) for PST files – resulting in a waiting thread hanging on re‑request. The cldflt.sys driver now correctly returns STATUS_PENDING with timeouts.

The last 10 Windows updates: