Insider New Windows Server 2025 LTSC Preview Build 26334.5000 - Dec. 5

Today we are pleased to release a new build of the next Windows Server Long-Term Servicing Channel (LTSC) Preview that contains both the Desktop Experience and Server Core installation options for Datacenter and Standard editions, Annual Channel for Container Host and Azure Edition (for VM evaluation only). Branding remains, Windows Server 2025, in this preview - when reporting issues please refer to Windows Server vNext preview. If you signed up for Server Flighting, you should receive this new build automatically.

Please note this will be the last Windows Server Insider Preview until January 2025. We look forward to seeing you in the new year!

What's 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. Introduced with 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

Windows Admin Center (WAC)​

Beginning with build 26252, Windows Server preview customers can download and install Windows Admin Center right from the Windows Server Desktop using the in-OS app that takes care of downloading and guides you through the installation process.


Note: You must be running a desktop version of Windows Server Datacenter or Standard preview to access this feature.

Windows Server Flighting is here!!​

If you signed up for Server Flighting, you should receive this new build automatically later today.

For more information, see Welcome to Windows Insider flighting on Windows Server - Microsoft Community Hub

Feedback Hub app is now available for Server Desktop users!​

The app should automatically update with the latest version, but if it does not, simply Check for updates in the app’s settings tab.

Known Issues​

Download Windows Server Insider Preview (microsoft.com)

Flighting: The label for this flight may incorrectly reference Windows 11. However, when selected, the package installed is the Windows Server update. Please ignore the label and proceed with installing your flight. This issue will be addressed in a future release.

Available Downloads​

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

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

Keys: Keys are valid for preview builds only

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

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

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

How to Download​

Registered Insiders may navigate directly to the Windows Server Insider Preview download page. If you have not yet registered as an Insider, see GETTING STARTED WITH SERVER on the Windows Insiders for Business portal.

We value your feedback!​

The most important part of the release cycle is to hear what's working and what needs to be improved, so your feedback is extremely valued. Beginning with Insider build 26063, please use the new Feedback Hub app for Windows Server if you are running a Desktop version of Server. If you are using a Core edition, or if you are unable to use the Feedback Hub app, you can use your registered Windows 10 or Windows 11 Insider device and use the Feedback Hub application. In the app, choose the Windows Server category and then the appropriate subcategory for your feedback. In the title of the Feedback, please indicate the build number you are providing feedback on as shown below to ensure that your issue is attributed to the right version:

[Server #####] Title of my feedback

See Give Feedback on Windows Server via Feedback Hub for specifics.

The Windows Server Insiders space on the Microsoft Tech Communities supports preview builds of the next version of Windows Server. Use the forum to collaborate, share and learn from experts. For versions that have been released to general availability in market, try the Windows Server for IT Pro forum or contact Support for Business.

Diagnostic and Usage Information​

Microsoft collects this information over the internet to help keep Windows secure and up to date, troubleshoot problems, and make product improvements. Microsoft server operating systems can be configured to turn diagnostic data off, send Required diagnostic data, or send Optional diagnostic data. During previews, Microsoft asks that you change the default setting to Optional to provide the best automatic feedback and help us improve the final product.

Administrators can change the level of information collection through Settings. For details, see Configure Windows diagnostic data in your organization (Windows 10 and Windows 11) - Windows Privacy. Also see the Microsoft Privacy Statement.

Terms of Use​

This is pre-release software - it is provided for use "as-is" and is not supported in production environments. Users are responsible for installing any updates that may be made available from Windows Update. All pre-release software made available to you via the Windows Server Insider program is governed by the Insider Terms of Use.






Check Windows Updates


ISO from Microsoft:



UUP Dump:

64-bit ISO download:

ARM64 ISO download: