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Announcing Windows Server vNext Preview Build 29651
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 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. Build 29531 established a new Server preview baseline build. Please perform a clean install of Build 29531 (or later) using the installation media linked below. Please note: Upgrades from Windows Server vNext preview builds older than 29531 are not supported. We encourage all Windows Server vNext preview users to perform a clean install using 29531 or later to successfully upgrade to future Windows Server vNext preview builds. While upgrades from earlier Windows Server previews (Build 26525 and older) are not technically blocked by setup.exe, a number of known issues have been identified related to upgrades necessitating the establishment of a new baseline build for our Server vNext Preview Program. The new baseline build (29531) will not be Flighted due to upgrade issues. Flighting support resumed with preview build 29550 or later. What's New Trusted Launch for virtual machines (TVMs) on Windows Server—a security feature you can enable when creating Generation 2 VMs. This initial preview supports TVMs with Secure Boot, vTPM, and vTPM state protection (at rest), managed via PowerShell. ⚠ Not supported in this release: Moving TVMs to another server TVMs in failover clusters or Hyper-V Replica Boot integrity verification TVMs in Windows Admin Center (WAC) Instructions 1. Install the latest ServerInsider preview build. 2. Enable Hyper-V (restarts the server): Install-WindowsFeature -Name Hyper-V -IncludeManagementTools -Restart 3. Set the registry keys: New-Item -Path "HKLM:\SOFTWARE\Microsoft\AszIgvmAgent" -Force New-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\AszIgvmAgent" -Name "TvmWinServer" -Value 1 -PropertyType DWord -Force 4. Enable Trusted Launch: Enable-WindowsOptionalFeature -Online -FeatureName "IsolatedGuestVm" -NoRestart 5. Verify IGVmAgent is running (should show Running): Get-Service -Name "IGVmAgent" If it isn't running, report the issue with the IGVmAgent and IGVmSystem Operational logs (Event Viewer → Applications and Services Logs → Microsoft → Windows). 6. Create an external virtual switch (if needed): (Get-VMSwitch | Where-Object { $_.SwitchType -eq "External" }).Name 7. Create the TVM. With an existing Gen 2 VHDX: New-VM -Name <VMName> -Generation 2 -GuestStateIsolationType TrustedLaunch -SwitchName <switch> -VHDPath <path to vhdx> -Path <config path> Or with a new VHD, then attach a Gen 2–compatible guest OS ISO: New-VM -Name <VMName> -SwitchName <switch> -NewVHDPath <new VHD path> -NewVHDSizeBytes 40GB -Generation 2 -GuestStateIsolationType TrustedLaunch -Path <config path> Add-VMDvdDrive -VMName <VMName> -Path <Guest OS ISO path> Ensure the DVD drive is first in the firmware boot order so the VM boots from it. 8. Verify isolation type (should return TrustedLaunch): (Get-VM -Name <VMName>).GuestStateIsolationType 9. Verify guest state protection: Stop the IGVmAgent service and restart the VM—without IGVmAgent running, a Trusted launch VM with guest state protection won't start. For more information, please review our blog post: Announcing Trusted Launch for Virtual Machines for Windows Server Insiders | Microsoft Community Hub Quick Machine Recovery available in Windows Server vNext Insider Previews. Quick machine recovery (QMR) is now available for Server vNext Insiders to test. This feature enables the recovery of Windows Server devices when they encounter boot critical errors that prevent them from booting. QMR can automatically search for cloud‑based remediations to recover from widespread boot failures significantly reducing the burden on IT administrators when multiple devices are impacted. This supports the goals of the Windows Resiliency Initiative by enabling applicable fixes to be delivered through trusted Windows Update to restore affected devices, helping reduce downtime and minimize manual recovery efforts across enterprise environments. This feature is currently enabled in the latest Server vNext Insider builds for customers to experience test mode. A Group Policy option to enable or disable the feature will be introduced in upcoming builds to provide additional administrative control. To simulate the quick machine recovery experience, use the following commands from an elevated command prompt: Enable test mode: reagentc.exe /SetRecoveryTestmode Configure Windows to boot to Windows Recovery Environment on the next boot: reagentc.exe /BootToRe Reboot your device.The system goes through autoremediation of a simulated crash safely and reboots back to Windows Server. For more information, please review Quick machine recovery (QMR) and Windows Resiliency Initiative. When providing feedback using Feedback hub, please select QMR from the Recovery and Uninstall category in the app. NVMe-over-Fabrics (NVMe-oF) extends the NVMe protocol—originally designed for local PCIe-attached SSDs—across a network fabric. Instead of using legacy SCSI-based protocols such as iSCSI or Fibre Channel, NVMe-oF allows a host to communicate directly with remote NVMe controllers using the same NVMe command set used for local devices. In this Insider build, Windows Server supports: NVMe-oF over TCP (NVMe/TCP), allowing NVMe-oF to run over standard Ethernet networks without specialized hardware. NVMe-oF over RDMA (NVMe/RDMA), enabling low-latency, high-throughput NVMe access over RDMA-capable networks (for example, RoCE or iWARP) using supported RDMA NICs. For more information, please visit: Introducing the Windows NVMe-oF Initiator Preview in Windows Server Insiders Builds | Microsoft Community Hub ReFS Boot is enabled for Windows Server vNext preview builds. Known Limitations ReFS Boot systems create a minimum 2GB WinRE partition. When WinRE cannot be updated due to space constraints, the system may disable WinRE. Disabling WinRE does not remove the partition. If the WinRE partition is deleted and the boot volume is extended over it, this operation is unrecoverable without a clean install. For more information, please visit: Resilient File System (ReFS) overview | Microsoft Learn Feedback Hub app is 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 A race condition in the TLS hybrid key exchange implementation may cause the LSASS service to crash when hybrid groups are negotiated by a TLS server. To avoid this issue until the fix is released, please disable hybrid groups (X25519_MLKEM768, SecP256r1_MLKEM768, SecP384r1_MLKEM1024) using TLS cmdlets or Group Policy, as outlined here. Server Core Upgrades and AppCompat FOD: Enabling AppCompat FOD after reinstall may fail due to legacy 3rd-party license compatibility issues on Server Core devices. Server Core users may be unable to install the latest AppCompat FOD after upgrading to build 29574. This appears to be limited to Server Core installations with 3rd-party application licenses that fail compatibility checks after upgrade. This will be addressed in a future build. Upgrading from older builds of Windows Server vNext previews (26525 or older) are not supported. Please perform a clean install of build 29531 or later. Users may experience failures when attempting to upgrade from earlier previews (build 26525 and older). VMs may fail to upgrade or start after upgrade from older preview builds impacting live migration and failover cluster scenarios. 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 vNext 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 October 15, 2027. 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. 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.803Views1like0CommentsAnnouncing Windows Server vNext Preview Build 29641
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 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. Build 29531 established a new Server preview baseline build. Please perform a clean install of Build 29531 (or later) using the installation media linked below. Please note: Upgrades from Windows Server vNext preview builds older than 29531 are not supported. We encourage all Windows Server vNext preview users to perform a clean install using 29531 or later to successfully upgrade to future Windows Server vNext preview builds. While upgrades from earlier Windows Server previews (Build 26525 and older) are not technically blocked by setup.exe, a number of known issues have been identified related to upgrades necessitating the establishment of a new baseline build for our Server vNext Preview Program. The new baseline build (29531) will not be Flighted due to upgrade issues. Flighting support resumed with preview build 29550 or later. What's New [NEW] Preview Build 29641 extends the expiration date of the preview builds into 2027. We're excited to announce Trusted Launch for virtual machines (TVMs) on Windows Server—a security feature you can enable when creating Generation 2 VMs. This initial preview supports TVMs with Secure Boot, vTPM, and vTPM state protection (at rest), managed via PowerShell. ⚠ Not supported in this release: Moving TVMs to another server TVMs in failover clusters or Hyper-V Replica Boot integrity verification TVMs in Windows Admin Center (WAC) Instructions Install the latest ServerInsider preview build. Enable Hyper-V (restarts the server): Install-WindowsFeature -Name Hyper-V -IncludeManagementTools -Restart Set the registry keys: New-Item -Path "HKLM:\SOFTWARE\Microsoft\AszIgvmAgent" -Force New-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\AszIgvmAgent" -Name "TvmWinServer" -Value 1 -PropertyType DWord -Force Enable Trusted Launch: Enable-WindowsOptionalFeature -Online -FeatureName "IsolatedGuestVm" -NoRestart Verify IGVmAgent is running (should show Running): Get-Service -Name "IGVmAgent" If it isn't running, report the issue with the IGVmAgent and IGVmSystem Operational logs (Event Viewer → Applications and Services Logs → Microsoft → Windows). Create an external virtual switch (if needed): (Get-VMSwitch | Where-Object { $_.SwitchType -eq "External" }).Name Create the TVM. With an existing Gen 2 VHDX: New-VM -Name <VMName> -Generation 2 -GuestStateIsolationType TrustedLaunch -SwitchName <switch> -VHDPath <path to vhdx> -Path <config path> Or with a new VHD, then attach a Gen 2–compatible guest OS ISO: New-VM -Name <VMName> -SwitchName <switch> -NewVHDPath <new VHD path> -NewVHDSizeBytes 40GB -Generation 2 -GuestStateIsolationType TrustedLaunch -Path <config path> Add-VMDvdDrive -VMName <VMName> -Path <Guest OS ISO path> Ensure the DVD drive is first in the firmware boot order so the VM boots from it. Verify isolation type (should return TrustedLaunch): (Get-VM -Name <VMName>).GuestStateIsolationType Verify guest state protection: Stop the IGVmAgent service and restart the VM—without IGVmAgent running, a Trusted launch VM with guest state protection won't start. For more information, please review our blog post: Announcing Trusted Launch for Virtual Machines for Windows Server Insiders | Microsoft Community Hub Quick Machine Recovery available in Windows Server vNext Insider Previews. Quick machine recovery (QMR) is now available for Server vNext Insiders to test. This feature enables the recovery of Windows Server devices when they encounter boot critical errors that prevent them from booting. QMR can automatically search for cloud‑based remediations to recover from widespread boot failures significantly reducing the burden on IT administrators when multiple devices are impacted. This supports the goals of the Windows Resiliency Initiative by enabling applicable fixes to be delivered through trusted Windows Update to restore affected devices, helping reduce downtime and minimize manual recovery efforts across enterprise environments. This feature is currently enabled in the latest Server vNext Insider builds for customers to experience test mode. A Group Policy option to enable or disable the feature will be introduced in upcoming builds to provide additional administrative control. To simulate the quick machine recovery experience, use the following commands from an elevated command prompt: 1. Enable test mode: reagentc.exe /SetRecoveryTestmode 2. Configure Windows to boot to Windows Recovery Environment on the next boot: reagentc.exe /BootToRe 3. Reboot your device. The system goes through autoremediation of a simulated crash safely and reboots back to Windows Server. For more information, please review Quick machine recovery (QMR) and Windows Resiliency Initiative. When providing feedback using Feedback hub, please select QMR from the Recovery and Uninstall category in the app. NVMe-over-Fabrics (NVMe-oF) extends the NVMe protocol—originally designed for local PCIe-attached SSDs—across a network fabric. Instead of using legacy SCSI-based protocols such as iSCSI or Fibre Channel, NVMe-oF allows a host to communicate directly with remote NVMe controllers using the same NVMe command set used for local devices. In this Insider build, Windows Server supports: NVMe-oF over TCP (NVMe/TCP), allowing NVMe-oF to run over standard Ethernet networks without specialized hardware. NVMe-oF over RDMA (NVMe/RDMA), enabling low-latency, high-throughput NVMe access over RDMA-capable networks (for example, RoCE or iWARP) using supported RDMA NICs. For more information, please visit: Introducing the Windows NVMe-oF Initiator Preview in Windows Server Insiders Builds | Microsoft Community Hub ReFS Boot is enabled for Windows Server vNext preview builds. Known Limitations ReFS Boot systems create a minimum 2GB WinRE partition. When WinRE cannot be updated due to space constraints, the system may disable WinRE. Disabling WinRE does not remove the partition. If the WinRE partition is deleted and the boot volume is extended over it, this operation is unrecoverable without a clean install. For more information, please visit: Resilient File System (ReFS) overview | Microsoft Learn Feedback Hub app is 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 A race condition in the TLS hybrid key exchange implementation may cause the LSASS service to crash when hybrid groups are negotiated by a TLS server. To avoid this issue until the fix is released, please disable hybrid groups (X25519_MLKEM768, SecP256r1_MLKEM768, SecP384r1_MLKEM1024) using TLS cmdlets or Group Policy, as outlined here. Server Core Upgrades and AppCompat FOD: Enabling AppCompat FOD after reinstall may fail due to legacy 3rd-party license compatibility issues on Server Core devices. Server Core users may be unable to install the latest AppCompat FOD after upgrading to build 29574. This appears to be limited to Server Core installations with 3rd-party application licenses that fail compatibility checks after upgrade. This will be addressed in a future build. Upgrading from older builds of Windows Server vNext previews (26525 or older) are not supported. Please perform a clean install of build 29531 or later. Users may experience failures when attempting to upgrade from earlier previews (build 26525 and older). VMs may fail to upgrade or start after upgrade from older preview builds impacting live migration and failover cluster scenarios. 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 vNext 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 October 15, 2027. 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. 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.919Views1like0CommentsWindows Server Datacenter: Azure Edition preview build 29641 now available in Azure
Hello Windows Server Insiders! We welcome you to try Windows Server vNext Datacenter: Azure Edition preview build 29641 in both Desktop experience and Core version on the Microsoft Server Operating Systems Preview offer in Azure. Azure Edition is optimized for operation in the Azure environment. For additional information, see Preview: Windows Server VNext Datacenter (Azure Edition) for Azure Automanage on Microsoft Docs. For more information about this build, see Announcing Windows Server vNext Preview Build 29641 | Microsoft Community Hub.127Views2likes0CommentsAnnouncing Windows Server vNext Preview Build 29621
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 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. Build 29531 established a new Server preview baseline build. Please perform a clean install of Build 29531 (or later) using the installation media linked below. Please note: Upgrades from Windows Server vNext preview builds older than 29531 are not supported. We encourage all Windows Server vNext preview users to perform a clean install using 29531 or later to successfully upgrade to future Windows Server vNext preview builds. While upgrades from earlier Windows Server previews (Build 26525 and older) are not technically blocked by setup.exe, a number of known issues have been identified related to upgrades necessitating the establishment of a new baseline build for our Server vNext Preview Program. The new baseline build (29531) will not be Flighted due to upgrade issues. Flighting support resumed with preview build 29550 or later. What's New [NEW] We're excited to announce Trusted Launch for virtual machines (TVMs) on Windows Server—a security feature you can enable when creating Generation 2 VMs. This initial preview supports TVMs with Secure Boot, vTPM, and vTPM state protection (at rest), managed via PowerShell. ⚠ Not supported in this release: Moving TVMs to another server TVMs in failover clusters or Hyper-V Replica Boot integrity verification TVMs in Windows Admin Center (WAC) Instructions 1. Install the latest ServerInsider preview build. 2. Enable Hyper-V (restarts the server): Install-WindowsFeature -Name Hyper-V -IncludeManagementTools -Restart 3. Set the registry keys: New-Item -Path "HKLM:\SOFTWARE\Microsoft\AszIgvmAgent" -Force New-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\AszIgvmAgent" -Name "TvmWinServer" -Value 1 -PropertyType DWord -Force 4. Enable Trusted Launch: Enable-WindowsOptionalFeature -Online -FeatureName "IsolatedGuestVm" -NoRestart 5. Verify IGVmAgent is running (should show Running): Get-Service -Name "IGVmAgent" If it isn't running, report the issue with the IGVmAgent and IGVmSystem Operational logs (Event Viewer → Applications and Services Logs → Microsoft → Windows). 6. Create an external virtual switch (if needed): (Get-VMSwitch | Where-Object { $_.SwitchType -eq "External" }).Name 7. Create the TVM. With an existing Gen 2 VHDX: New-VM -Name <VMName> -Generation 2 -GuestStateIsolationType TrustedLaunch -SwitchName <switch> -VHDPath <path to vhdx> -Path <config path> Or with a new VHD, then attach a Gen 2–compatible guest OS ISO: New-VM -Name <VMName> -SwitchName <switch> -NewVHDPath <new VHD path> -NewVHDSizeBytes 40GB -Generation 2 -GuestStateIsolationType TrustedLaunch -Path <config path> Add-VMDvdDrive -VMName <VMName> -Path <Guest OS ISO path> Ensure the DVD drive is first in the firmware boot order so the VM boots from it. 8. Verify isolation type (should return TrustedLaunch): (Get-VM -Name <VMName>).GuestStateIsolationType 9. Verify guest state protection: Stop the IGVmAgent service and restart the VM—without IGVmAgent running, a Trusted launch VM with guest state protection won't start. For more information, please review our blog post: Announcing Trusted Launch for Virtual Machines for Windows Server Insiders | Microsoft Community Hub Quick Machine Recovery available in Windows Server vNext Insider Previews. Quick machine recovery (QMR) is now available for Server vNext Insiders to test. This feature enables the recovery of Windows Server devices when they encounter boot critical errors that prevent them from booting. QMR can automatically search for cloud‑based remediations to recover from widespread boot failures significantly reducing the burden on IT administrators when multiple devices are impacted. This supports the goals of the Windows Resiliency Initiative by enabling applicable fixes to be delivered through trusted Windows Update to restore affected devices, helping reduce downtime and minimize manual recovery efforts across enterprise environments. This feature is currently enabled in the latest Server vNext Insider builds for customers to experience test mode. A Group Policy option to enable or disable the feature will be introduced in upcoming builds to provide additional administrative control. To simulate the quick machine recovery experience, use the following commands from an elevated command prompt: Enable test mode: reagentc.exe /SetRecoveryTestmode Configure Windows to boot to Windows Recovery Environment on the next boot: reagentc.exe /BootToRe Reboot your device. The system goes through autoremediation of a simulated crash safely and reboots back to Windows Server. For more information, please review Quick machine recovery (QMR) and Windows Resiliency Initiative. When providing feedback using Feedback hub, please select QMR from the Recovery and Uninstall category in the app. NVMe-over-Fabrics (NVMe-oF) extends the NVMe protocol—originally designed for local PCIe-attached SSDs—across a network fabric. Instead of using legacy SCSI-based protocols such as iSCSI or Fibre Channel, NVMe-oF allows a host to communicate directly with remote NVMe controllers using the same NVMe command set used for local devices. In this Insider build, Windows Server supports: NVMe-oF over TCP (NVMe/TCP), allowing NVMe-oF to run over standard Ethernet networks without specialized hardware. NVMe-oF over RDMA (NVMe/RDMA), enabling low-latency, high-throughput NVMe access over RDMA-capable networks (for example, RoCE or iWARP) using supported RDMA NICs. For more information, please visit: Introducing the Windows NVMe-oF Initiator Preview in Windows Server Insiders Builds | Microsoft Community Hub ReFS Boot is enabled for Windows Server vNext preview builds. Known Limitations ReFS Boot systems create a minimum 2GB WinRE partition. When WinRE cannot be updated due to space constraints, the system may disable WinRE. Disabling WinRE does not remove the partition. If the WinRE partition is deleted and the boot volume is extended over it, this operation is unrecoverable without a clean install. For more information, please visit: Resilient File System (ReFS) overview | Microsoft Learn Feedback Hub app is 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 A race condition in the TLS hybrid key exchange implementation may cause the LSASS service to crash when hybrid groups are negotiated by a TLS server. To avoid this issue until the fix is released, please disable hybrid groups (X25519_MLKEM768, SecP256r1_MLKEM768, SecP384r1_MLKEM1024) using TLS cmdlets or Group Policy, as outlined here. Server Core Upgrades and AppCompat FOD: Enabling AppCompat FOD after reinstall may fail due to legacy 3rd-party license compatibility issues on Server Core devices. Server Core users may be unable to install the latest AppCompat FOD after upgrading to build 29574. This appears to be limited to Server Core installations with 3rd-party application licenses that fail compatibility checks after upgrade. This will be addressed in a future build. Upgrading from older builds of Windows Server vNext previews (26525 or older) are not supported. Please perform a clean install of build 29531 or later. Users may experience failures when attempting to upgrade from earlier previews (build 26525 and older). VMs may fail to upgrade or start after upgrade from older preview builds impacting live migration and failover cluster scenarios. 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 vNext 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, 2026. 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. 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.1.8KViews2likes0Comments
HLK test failing for a KMDF driver with error “A lower driver failed IRP_MN_QUERY_STOP_DEVICE”
Subject: HLK DF‑PNP Rebalance Fail Restart Device: E: target widens to all volumes; QueryStop fails even without my driver installed. Hi all, I’m trying to pass all HLK tests for my driver. Driver: KMDF PnP volume upper‑filter (attached via UpperFilters to the Volume/Disk class) OS: Windows Server 2016 Datacenter, build 14393 HLK: 10.1.14393.8069 Test: DF - PNP Rebalance Fail Restart Device (Reliability) Target volume: E: (NTFS) Storage: PERC H330 Mini (DELL) (HBA) Observed behavior The DQ initially targets E:, but the test later widens to all STORAGE\Volume devnodes: WDTF_TARGETS : INFO : - Query("IsDevice AND (DriverBinaryNames!='i8042prt.sys') AND (Class!=hdc) AND (Class!=scsiadapter) AND (DsmDevice!=TRUE) AND (IsDevice AND (DriverBinaryNames!='i8042prt.sys') AND (Class!=hdc) AND (Class!=scsiadapter) AND (DsmDevice!=TRUE) AND (DeviceID='STORAGE\VOLUME{01FEB6F1-3717-11F1-9707-806E6F6E6963}#0000000001000000'))") WDTF_TARGETS : INFO : Target: Volume (E:) STORAGE\VOLUME{01FEB6.. WDTF_SUPPORT : INFO : - ClearSetupAPILogs() WDTF_TARGETS : INFO : - Query("IsDevice AND (SemiUniqueTargetHardwareIdentifier='STORAGE\Volume')") WDTF_TARGETS : INFO : Target: Volume STORAGE\VOLUME{01FEB6.. WDTF_TARGETS : INFO : Target: Volume STORAGE\VOLUME{01FEB6.. WDTF_TARGETS : INFO : Target: Volume (C:) STORAGE\VOLUME{01FEB6.. WDTF_TARGETS : INFO : Target: Volume (E:) STORAGE\VOLUME{01FEB6.. Failures report A lower driver failed IRP_MN_QUERY_STOP_DEVICE and PNP.RestartDevice() Win32=1 - Incorrect function. For each of the 4 target volumes, it shows this error, DTF_PNP : INFO : - EDTTryStopDeviceFailRestart() WDTF_PNP : INFO : Target: Volume (C:) STORAGE\VOLUME{01FEB6EF-3717-11F1-9707-806E6F6E6963}#000000001F500000 WDTF_PNP : INFO : Result: A lower driver failed IRP_MN_QUERY_STOP_DEVICE. Rebalance tests cannot proceed... WDTF_PNP : INFO : - EDTTryStopDeviceFailRestart() WDTF_PNP : INFO : Target: Volume (E:) STORAGE\VOLUME{01FEB6F1-3717-11F1-9707-806E6F6E6963}#0000000001000000 WDTF_PNP : INFO : Result: A lower driver failed IRP_MN_QUERY_STOP_DEVICE. Rebalance tests cannot proceed... WDTF_PNP : ERROR : PNP.RestartDevice() Win32=1 - Incorrect function. WDTF_PNP : ERROR : PNP.RestartDevice() Win32=1 - Incorrect function. Q1. I have tried multiple variations of the DQ query, and each successfully targets the E volume only. Why does this test later widen to all volumes even when DQ targets only E:? How can I force it to stay on E: ? Q2. I also ran this on a physical server client and a VM client, but faced the same issue both times. I understand the system/boot volume may veto QueryStop, but why does each volume report ‘a lower driver failed IRP_MN_QUERY_STOP_DEVICE’ in this test? Q3. I uninstalled my driver completely and still see the same failures when the test is running with only inbox drivers (e.g., msdmfilt.sys, volsnap.sys, volume.sys) listed by Driver Verifier for target E in the logs. That makes me suspect setup/config rather than my driver. Why would only these drivers fail the test as well, what am I missing here? WDTF_DRIVER_VERIFIER : INFO : - EnableOnAllDriversOfDevices() WDTF_DRIVER_VERIFIER : INFO : Target: Volume (E:) STORAGE\VOLUME{01FEB6F1-3717-11F1-9707-806E6F6E6963}#0000000001000000 WDTF_DRIVER_VERIFIER : INFO : Driver: msdmfilt.sys WDTF_DRIVER_VERIFIER : INFO : Driver: volsnap.sys WDTF_DRIVER_VERIFIER : INFO : Driver: volume.sys Thanks for any guidance!111Views0likes1CommentWindows Server Datacenter: Azure Edition preview build 29621 now available in Azure
Hello Windows Server Insiders! We welcome you to try Windows Server vNext Datacenter: Azure Edition preview build 29621 in both Desktop experience and Core version on the Microsoft Server Operating Systems Preview offer in Azure. Azure Edition is optimized for operation in the Azure environment. For additional information, see Preview: Windows Server VNext Datacenter (Azure Edition) for Azure Automanage on Microsoft Docs. For more information about this build, see Announcing Windows Server vNext Preview Build 29621 | Microsoft Community Hub.147Views1like0Comments
Multiple Namespace Detection in Windows NVMe Over TCP Initiator
We are evaluating the Windows NVMe Initiator and have observed an issue with namespace handling. Our NVMe subsystem contains multiple namespaces. When we connect to the subsystem over TCP and establish connections to all namespaces, they are all shown as connected under the controller. However, only one namespace (shared block device) is exposed and accessible within Windows. Based on our testing, it appears that the initiator may be mapping only the first namespace associated with a given Friendly Name. We were able to connect another subsystem, whose friendly name was different. Questions: Is support for multiple namespaces within a single subsystem currently available in the Windows NVMe Initiator? If so, are there any configuration requirements or known limitations related to namespace discovery and mapping? Is the initiator expected to expose all connected namespaces as separate disks within Windows? We would appreciate any guidance or clarification on the expected behavior.88Views0likes2CommentsWindows Crash During NVMe Over TCP Disk Disconnect
While evaluating the Windows NVMe Initiator, we have observed that disconnecting an NVMe disk frequently results in a Windows system crash. This occurs during the disconnect operation and appears to be reproducible in our test environment. Questions: Has anyone else encountered similar behavior? Are there any known issues related to NVMe/TCP disconnect handling? Are there recommended troubleshooting steps, logs, or diagnostics that we should collect to help identify the root cause? Any insights would be greatly appreciated.51Views0likes1Comment
