Windows Server 2025 Insider Preview: Build 26311 Now Available for Download

Microsoft has unveiled its latest Windows Server build for participants in the Windows Server Insider Program, identified as build number 26311. Notably, this and upcoming builds are now branded under the Windows Server 2025 name.

Regrettably, the changelog released by Microsoft for the Windows Server 2025 preview build 26311 mirrors that of the previous preview build, 26304. The earlier version introduced a significant enhancement—the Windows Defender Application Control for Business (WDAC)—which integrates additional security features aimed at bolstering Windows Server 2025.

With this context in mind, here is the changelog information for Windows Server 2025 preview build 26311:

New Features

[NEW] Windows Defender Application Control for Business (WDAC)

The Windows Defender Application Control (WDAC) for business provides a protective software layer that minimizes vulnerabilities by enforcing a specified list of approved software. For Windows Server 2025, a Microsoft-defined ‘default policy’ is made available, which can be implemented via PowerShell cmdlets utilizing our security configuration platform known as ‘OSconfig’.

Windows Server 2025 Security Baseline Preview

Starting from build 26296, we are excited to announce the launch of the Windows Server 2025 Security Baseline Preview. You can enhance security right away by implementing the recommended security stance for your device or VM role through the application of a customized security baseline. This includes over 350 preconfigured Windows security settings that help enforce detailed security protocols based on Microsoft and industry best practices. The Windows Server 2025 Security Baseline content is categorized into three key sections based on server roles:

Domain Controller (DC)

Member Server

Workgroup Member

Windows Server Flighting is here!

If you are enrolled in Server Flighting, you will receive this new build automatically later today. For further details, please visit Welcome to Windows Insider flighting on Windows Server – Microsoft Community Hub.

The application is expected to update automatically with the latest version; however, if that does not happen, you can manually check for updates in the app’s settings.

Known Issues

Download Windows Server Insider Preview (microsoft.com)

Flighting: The flight label may mistakenly indicate Windows 11. However, when selected, the installed package will actually be for Windows Server. Please disregard the incorrect label and proceed with the installation. This issue will be addressed in a future update.

WinPE – PowerShell Scripts: Installing the WinPE-PowerShell optional component does not correctly set up PowerShell in WinPE, resulting in the failure of PowerShell cmdlets. Users relying on PowerShell in WinPE should avoid this build.

If you are testing upgrades from Windows Server 2019 or 2022, it’s advised to refrain from using this build, as there are intermittent upgrade failures associated with it.

This build has an issue where archiving event logs via the “wevetutil al”command can cause the Windows Event Log service to crash, resulting in failed archiving. The service can be restarted by executing “Start-Service EventLog”from an administrative command prompt.

For those with Secure Launch/DRTM code paths activated, it is recommended not to install this current build.

Available Downloads

Availability of downloads may be restricted in certain regions. For more details, refer to Microsoft suspends new sales in Russia – Microsoft On the Issues.

Windows Server Long-Term Servicing Channel Preview available in ISO format in 18 languages, and in VHDX format (English only).

Windows Server Datacenter Azure Edition Preview available in both ISO and VHDX formats (English only).

Microsoft Server Languages and Optional Features Preview

Keys: Keys provided are valid solely for preview builds:

Server Standard: MFY9F-XBN2F-TYFMP-CCV49-RMYVH

Datacenter: 2KNJJ-33Y9H-2GXGX-KMQWH-G6H67

Azure Edition does not require a key.

Symbols: Symbols can be accessed via the public symbol server; see Using the Microsoft Symbol Server.

Expiration: This Windows Server Preview is set to expire on September 15, 2025.