Announcing Windows Server vNext Preview Build 29595
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 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 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.Announcing Windows Server vNext Preview Build 29585
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. Please join us this week for Windows Server Summit 2026 Windows Server Summit 2026 is happening this week (May 11 - May 13). Please join us for this online event to learn about the latest updates in Windows Server 2025 and what's coming in vNext. For more information and to register, please visit Windows Server Summit - May 11-13, 2026 - Microsoft Event page. What's New 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 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.
Windows NVMe-oF Initiator connect error
Hi everyone, I am trying to test the new Windows NVMe-oF Initiator within build 29550.1000 but I am not able to connect to a remote storage array - getting the error "IOCTL_NVMEOF_CONNECT_CONTROLLER failed with error code 0x1f" (see screenshot). Any idea what does this error mean or what can be wrong?
Capabilities of NVMe-oF so far?
Started playing around with NVMe-oF last night and got a successful connection to TrueNAS. I'm wondering what the current capabilities/limitations are. As far as I can tell you can't cluster the disk which is what I was primarily interested in. I was able to connect the same NQN endpoint to two servers but the WSFC cluster wouldn't detect it as a cluster available disk. Also the disks seems to disappear on every reboot and has to be set up again, so is there no auto-mount yet? I understand this is early preview so I don't have many expectations, just would like some clarity. Thank you.Windows NVMe-oF Initiator
Hi everyone, I am trying to test the new Windows NVMe-oF Initiator within build 29550.1000 but I am not able to configure an I/O Subsystem Port, still getting the message " A Host Gateway with the specified identifier was not found for the Initiator Adapter." (see screenshot). Any idea what I am doing wrong?
NTFS permissions are partially not working.
Participant A is sometimes unable to see Participant B’s files. The issue can be resolved by clicking the option: "Replace all child object permission entries with inheritable permission entries from this object." However, the problem keeps reappearing. Windows Server 2022 Datacenter (VMware 7.1), formatted as NTFS.Shadow Copy with 6 days delay
a { text-decoration: none; color: #464feb; } tr th, tr td { border: 1px solid #e6e6e6; } tr th { background-color: #f5f5f5; } Shadow Copy Windows Server 2022 Datacenter (VMWare 7.1) The MaxShadowCopies registry value has been increased to 256. Shadow Copies have been redirected to a different hard disk; FS=NTFS. The schedule is set to run three times per day. The maximum size is set to “Limit” with 1,700,000 MB. Current issue: Shadow Copies were available normally for several months. Now, suddenly, the Shadow Copies are displayed with a 6‑day delay.
vNVMe on Hyper-V to unlock PCIe 5.0 NVMe performance
On hosts with NVMe PCIe 5.0 (E3.S/U.2), Hyper-V guests still use virtual SCSI and leave a lot of performance on the table. We are paying for top-tier storage, yet software becomes the limiter. A virtual NVMe device that preserves checkpoints/Replica/Live Migration would align guest performance with modern hardware without forcing DDA and its operational trade-offs.
