Windows 11 KB5068221 (OS Build 26100.6588) released
Microsoft has released an out-of-band (OOB) update for Windows 11 24H2, denoted as KB5068221 with the build number 26100.6588. This cumulative update includes essential security fixes along with quality improvements that have been incorporated from the September 9, 2025, security update (KB5065426).
The latest OOB update addresses a critical issue that affects Microsoft Office applications running within Microsoft Application Virtualization (App-V) environments. The problem arose due to a double handle closure in either AppVEntSubsystems32 or AppVEntSubsystems64 system components. This problem has been addressed, providing a seamless experience for users utilizing these virtualized environments.
Furthermore, this release brings updates to the following AI components:
The Image Search component has been updated to version 1.2508.906.0, while similar updates have also been implemented in Content Extraction (version 1.2508.906.0), Semantic Analysis (version 1.2508.906.0), and Settings Model (version 1.2508.906.0). These AI component upgrades aim to enhance the overall performance of Windows 11.
Additionally, this update includes a new version of the Windows 11 servicing stack (KB5064531) with build number 26100.5074. The primary goal of servicing stack updates (SSUs) is to ensure that devices can reliably receive and install Microsoft updates by maintaining a robust servicing stack.
However, there are some known issues associated with this update. Specifically, users may experience difficulties in connecting to shared files and folders using the Server Message Block (SMB) v1 protocol on NetBIOS over TCP/IP (NetBT). This issue typically arises after installing this Windows update, especially if either the SMB client or server has the September 2025 security update installed.
It is essential to note that the SMBv1 protocol is no longer installed by default in modern versions of Windows and Windows Server due to its deprecation. This issue does not affect deployments using newer versions of the protocol (SMBv2 or SMBv3).
To resolve the connectivity problem, users can temporarily enable network traffic on TCP port 445. This will allow the Windows SMB connection to switch automatically from NetBT to TCP and successfully reconnect.
Microsoft is actively working on a permanent resolution for this issue, which will be addressed in an upcoming Windows update.
September 22, 2025—KB5068221 (OS Build 26100.6588) Out-of-band - Microsoft Support
September 22, 2025—KB5068221 (OS Build 26100.6588) Out-of-band - Microsoft Support
