Announcing Windows Server Preview Build 26257

Hello Windows Server Insiders!

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 has been updated for the upcoming release, Windows Server 2025, in this preview – when reporting issues please refer to Windows Server 2025 preview.  If you signed up for Server Flighting, you should receive this new build automatically.

What’s New

Windows Admin Center (WAC)
Beginning with build 26252, Windows Server 2025 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 2025 Datacenter or Standard preview to access this feature.  

Delegated Managed Service Accounts (dMSA)

A new account type known as delegated Managed Service Account (dMSA) is now available that allows migration from a traditional service account to a machine account with managed and fully randomized keys, while disabling original service account passwords.

Authentication for dMSA is linked to the device identity, which means that only specified machine identities mapped in AD can access the account. Using dMSA helps to prevent harvesting credentials using a compromised account (kerberoasting), which is a common issue with traditional service accounts.

To learn more about dMSA, visit https://learn.microsoft.com/en-us/windows-server/security/delegated-managed-service-accounts/delegated-managed-service-accounts-overview.

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

The new 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

Upgrade does not complete: Some users may experience an issue when upgrading where the download process does not progress beyond 0%.  If you encounter this issue, please upgrade to this newer build using the ISO media download option. Download Windows Server Insider Preview (microsoft.com)

Access denied error when using Diskpart –> Clean Image on Winpe.vhdx VMs created using WinPE: Create bootable media | Microsoft Learn. We are working to resolve this issue and expect to have it fixed in the next preview release.

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.

 Setup: Some users may experience overlapping rectangle voids following mouse clicks during “OOBE” setup. This is a graphics rendering issue and will not prevent setup from completing. This issue will be addressed in a future release.

WinPE – Powershell Scripts: Applying the WinPE-Powershell optional component does not properly install Powershell in WinPE. As a result, Powershell cmdlets will fail. Customers who are dependent on Powershell in WinPE should not use this build.

If you are validating upgrades from Windows Server 2019 or 2022, we do not recommend that you use this build as intermittent upgrade failures have been identified for this build.

This build has an issue where archiving eventlogs with “wevetutil al” command causes the Windows Event Log service to crash, and the archive operation to fail. The service must be restarted by executing “Start-Service EventLog” from an administrative command line prompt.

If you have Secure Launch/DRTM code path enabled, we do not recommend that you install this build. 

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, 2024.

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 http://aka.ms/winserverdata. 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.

​Announcing Windows Server Preview Build 26257
Hello Windows Server Insiders!
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 has been updated for the upcoming release, Windows Server 2025, in this preview – when reporting issues please refer to Windows Server 2025 preview.  If you signed up for Server Flighting, you should receive this new build automatically.
 
What’s New
Windows Admin Center (WAC)Beginning with build 26252, Windows Server 2025 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 2025 Datacenter or Standard preview to access this feature.  
 
Delegated Managed Service Accounts (dMSA)
A new account type known as delegated Managed Service Account (dMSA) is now available that allows migration from a traditional service account to a machine account with managed and fully randomized keys, while disabling original service account passwords.
 
Authentication for dMSA is linked to the device identity, which means that only specified machine identities mapped in AD can access the account. Using dMSA helps to prevent harvesting credentials using a compromised account (kerberoasting), which is a common issue with traditional service accounts.
To learn more about dMSA, visit https://learn.microsoft.com/en-us/windows-server/security/delegated-managed-service-accounts/delegated-managed-service-accounts-overview.
 
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
 
The new 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
Upgrade does not complete: Some users may experience an issue when upgrading where the download process does not progress beyond 0%.  If you encounter this issue, please upgrade to this newer build using the ISO media download option. Download Windows Server Insider Preview (microsoft.com)
   
Access denied error when using Diskpart –> Clean Image on Winpe.vhdx VMs created using WinPE: Create bootable media | Microsoft Learn. We are working to resolve this issue and expect to have it fixed in the next preview release.
 
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.
 
 Setup: Some users may experience overlapping rectangle voids following mouse clicks during “OOBE” setup. This is a graphics rendering issue and will not prevent setup from completing. This issue will be addressed in a future release.
 
WinPE – Powershell Scripts: Applying the WinPE-Powershell optional component does not properly install Powershell in WinPE. As a result, Powershell cmdlets will fail. Customers who are dependent on Powershell in WinPE should not use this build.
 
If you are validating upgrades from Windows Server 2019 or 2022, we do not recommend that you use this build as intermittent upgrade failures have been identified for this build.
 
This build has an issue where archiving eventlogs with “wevetutil al” command causes the Windows Event Log service to crash, and the archive operation to fail. The service must be restarted by executing “Start-Service EventLog” from an administrative command line prompt.
 
If you have Secure Launch/DRTM code path enabled, we do not recommend that you install this build. 
 
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, 2024.
 
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 http://aka.ms/winserverdata. 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.  Read More

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