Windows Server 2025 Insider Preview build 26311 is now available

Microsoft has released the latest Windows Server build for Windows Server Insider Program members, with the new build numbered 26311. Notably, this and upcoming Windows Server Insider builds are now branded under Windows Server 2025.

However, the official changelog provided by Microsoft for Windows Server 2025 preview build 26311 remains the same as the changelog from the previous preview build, version 26304. That prior build introduced a significant feature, Windows Defender Application Control for Business (WDAC), which brings additional security enhancements to Windows Server 2025.

With that in mind, here is the official changelog for Windows Server 2025 preview build 26311:

What’s New

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

Windows Defender Application Control (WDAC) for business is a software-based security layer that reduces attack surface by enforcing an explicit list of software that is allowed to run. For Windows Server 2025, we have provided Microsoft defined ‘default policy’ which can be applied to the server via PowerShell cmdlets, powered by our ‘Security configuration platform called ‘OSconfig’. To learn more, please review Windows Defender Application Control for Business (WDAC) – Microsoft Community Hub.

Starting with build 26296, we’re excited to introduce the Windows Server 2025 Security Baseline Preview. This feature allows you to establish security configurations from the beginning, applying a tailored security baseline specific to your device or VM role. With over 350 preconfigured security settings, this baseline helps enforce granular security aligned with best practices recommended by Microsoft and industry standards. The security baseline for Windows Server 2025 is organized into three role-specific categories:

• Domain Controller (DC)
• Member Server
• Workgroup Member

Note: The security baseline should only be previewed on test systems. While a ‘Remove’ command is available, not all configurations are fully reversible. For more information, see “Announcing Windows Server 2025 Security Baseline Preview” on Microsoft Community Hub.

Windows Server Flighting Has Arrived!

If you’ve signed up for Server Flighting, this new build will be delivered to you automatically later today. For more information, visit “Welcome to Windows Insider flighting on Windows Server” on Microsoft Community Hub.

New Feedback Hub App Available

Server Desktop users now have access to the updated Feedback Hub app, which should automatically install the latest version. If not, you can update manually through the app’s settings tab.

Known Issues

1. Flight Label: The flight label may mistakenly reference Windows 11. However, selecting this option will install the correct Windows Server update. Please disregard the label; it will be corrected in a future update.
2. WinPE – PowerShell Scripts: The WinPE-PowerShell component does not correctly install PowerShell in WinPE, leading to PowerShell cmdlet failures. Avoid using this build if you rely on PowerShell in WinPE.
3. Upgrades from Windows Server 2019 or 2022: Upgrade testing is not recommended with this build due to identified intermittent upgrade failures.
4. Event Log Service Crash: Using the “wevetutil al” command to archive event logs may cause the Windows Event Log service to crash. Restart the service with “Start-Service EventLog” from an admin command line if needed.
5. Secure Launch/DRTM Code Path: We advise against installing this build if you have Secure Launch/DRTM enabled.

Available Downloads

Downloads to certain countries may not be available. See Microsoft suspends new sales in Russia – Microsoft On the Issues.

Available downloads include:

• Windows Server Long-Term Servicing Channel Preview: ISO in 18 languages, VHDX in English only.
• Windows Server Datacenter Azure Edition Preview: ISO and VHDX, English only.
• Microsoft Server Languages and Optional Features Preview

Keys: Preview builds only.

• Server Standard: MFY9F-XBN2F-TYFMP-CCV49-RMYVH
• Datacenter: 2KNJJ-33Y9H-2GXGX-KMQWH-G6H67
• Azure Edition does not require a key.

Symbols: Available on the public symbol server – see Using the Microsoft Symbol Server.

Expiration: This Windows Server Preview will expire on September 15, 2025.

You can download the new Windows Server preview from Microsoft’s site.

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