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Announcing Windows Server vNext Preview Build 29550
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 earlier 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 a release 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 resumes with preview build 29550 or later. What's New 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 Upgrading from earlier 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 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.Bookmark the Secure Boot playbook for Windows Server
Secure Boot is a long‑standing security capability that works in conjunction with the Unified Extensible Firmware Interface (UEFI) to confirm that firmware and boot components are trusted before they are allowed to run. Microsoft is updating the Secure Boot certificates originally issued in 2011 to ensure Windows devices continue to verify trusted boot software. These older certificates begin expiring in June 2026. While Windows Server 2025 certified server platforms already include the 2023 certificates in firmware. For servers that do not, you will need to manually update the certificates. Unlike Windows PCs, which may receive the 2023 Secure Boot certificates through Controlled Feature Rollout (CFR) as part of the monthly update process, Windows Server requires manual action. Luckily, there is a step=by-step guide to help! With the Secure Boot Playbook for Windows Server, you'll find information on the tools and options available to help you update Secure Boot certificates on Windows Server. Check it out today!CrowdStrike Secure Boot Lifecycle Management Content Pack
CrowdStrike has recently released the Secure Boot Lifecycle Management Content Pack. This new feature helps Falcon for IT module users manage Windows Secure Boot certificate updates ahead of these certificates’ expiration beginning in late June 2026. The dashboard provides an at‑a‑glance view of Secure Boot–enabled devices, showing which systems are already compliant with the updated 2023 Secure Boot certificate, which are in progress, and which are blocked or require opt‑in to a managed rollout. It also highlights certificate update failures that may require investigation. In addition, overall readiness is summarized through a compliance gauge, while a 30‑day trend shows how pass and fail counts change as remediation progresses. Filters by operating system, server edition, hostname, and update status help administrators quickly identify devices that need action to help ensure systems remain secure after the certificates expire. The feature also provides management options to opt devices into Microsoft's managed rollout for gradual, tested deployment, and to block updates on hardware with known compatibility issues to prevent boot failures. Note that this feature is available as part of CrowdStrike's Falcon for IT module. CrowdStrike Endpoint Detection and Response (EDR) customers who are not licensed for this module can enable a free trial from the CrowdStrike Store. To learn more about this feature, please see the content pack tutorial video.
PS script for moving clustered VMs to another node
Windows Server 2022, Hyper-V, Failover cluster We have a Hyper-V cluster where the hosts reboot once a month. If the host being rebooted has any number of VMs running on it the reboot can take hours. I've proven this by manually moving VM roles off of the host prior to reboot and the host reboots in less than an hour, usually around 15 minutes. Does anyone know of a powershell script that will detect clustered VMs running on the host and move them to another host within the cluster? I'd rather not reinvent this if someone's already done it.
Groups and roles issues
Hello, We use two user accounts, one that is a server administrator and that we use to connect to the servers via RDP (ADMaccounts). The other is not an administrator and we use it on our workstations (USRaccounts). I deleted from Gateway Users the Builtin\users group because I don't want users to access even though they can't do anything. For now I added another group as Gateway Users with our USR accounts. ADM accounts are member of Gateway Administrators. When Im logged into WAC with the ADM user and access to WAC, the browser asks me for credentials, I enter the ADM credentials, and I log in. When I am at my workstation, I access the URL and log in without being asked for credentials with the USR account session. I do not understand this behavior. I need to access from my workstation with the ADM account. How can I make the browser ask me for credentials? Do I have to open the browser with the admin credentials every time I want to manage WAC? Thanks, Best regards
CSV Auto-Pause on Windows Server 2025 Hyper-V Cluster
Hi everyone, i'm facing a very strange behavior with a newly created HyperV Clsuter running on Windows Server 2025. One of the two nodes keep calling for autopause on the CSV during the I/O peak. Does anyone have experienced this ? Here are the details : Environment Cluster: 2-node Failover Cluster Nodes: HV1 & HV2 (HPE ProLiant DL360 Gen11) OS: Windows Server 2025 Datacenter, Build 26100.32370 (KB5075899 installed Feb 21, 2026) Storage: HPE MSA 2070 full SSD, iSCSI point-to-point (4×25 Gbps per node, 4 MPIO paths) CSV: Single volume "Clsuter Disk 2" (~14 TB, NTFS, CSVFS_NTFS) Quorum: Disk Witness (Node and Disk Majority) Networking: 4×10 Gbps NIC Teaming for management/cluster/VMs traffic, dedicated iSCSI NICs Problem Description The cluster experiences CSV auto-pause events daily during a peak I/O period (~10:00-11:30), caused by database VMs generating ~600-800 MB/s (not that much). The auto-pause is triggered by HV2's CsvFs driver, even though HV2 hosts no VMs. All VMs run on HV1, which is the CSV coordinator/owner. Comparative Testing (Feb 23-26, 2026) Date HV2 Status Event 5120 SMB Slowdowns (1054) Auto-pause Cycles VM Impact Feb 23 Active 1 44 1 cycle (237ms recovery) None Feb 24 Active 0 8 0 None Feb 25 Drained (still in cluster) 4 ~60 (86,400,000ms max!) 3 cascade cycles Severe - all VMs affected Feb 26 Powered off 0 0 0 None Key finding: Draining HV2 does NOT prevent the issue. Only fully powering off HV2 eliminates all auto-pause events and SMB slowdowns during the I/O peak. Root Cause Analysis 1. CsvFs Driver on HV2 Maintains Persistent SMB Sessions to CSV SMB Client Connectivity log (Event 30833) on HV2 shows ~130 new SMB connections per hour to the CSV share, continuously, constant since boot: Share: \\xxxx::xxx:xxx:xxx:xxx\xxxxxxxx-...-xxxxxxx$ (HV1 cluster virtual adapter) All connections from PID 4 (System/kernel) — CsvFs driver 5,649 connections in 43.6 hours = ~130/hour Each connection has a different Session ID (not persistent) This behavior continues even when HV2 is drained 2. HV2 Opens Handles on ALL VM Files During the I/O peak on Feb 25, SMB Server Operational log (Event 1054) on HV1 showed HV2 blocking on files from every VM directory, including powered-off VMs and templates: .vmgs, .VMRS, .vmcx, .xml — VM configuration and state files .rct, .mrt — RCT/CBT tracking files Affected VMs: almost all Also affected: powered-off VMs And templates: winsrv2025-template 3. Catastrophic Block Durations On Feb 25 (HV2 drained but still in cluster): Operations blocked for 86,400,000 ms (exactly 24 hours) — handles accumulated since previous day These all expired simultaneously at 10:13:52, triggering cascade auto-pause Post-autopause: big VM freeze/lag for additional 2,324 seconds (39 minutes) On Feb 24 (HV2 active): Operations blocked for 1,150,968 ms (19 minutes) on one of the VM files Despite this extreme duration, no auto-pause was triggered that day 4. Auto-pause Trigger Mechanism HV2 Diagnostic log at auto-pause time: CsvFs Listener: CsvFsVolumeStateChangeFromIO->CsvFsVolumeStateDraining, status 0xc0000001 OnVolumeEventFromCsvFs: reported VolumeEventAutopause to node 1 Error status 0xc0000001 (STATUS_UNSUCCESSFUL) on I/O operation from HV2 CsvFsVolumeStateChangeFromIO = I/O failure triggered the auto-pause HV2 has no VMs running — this is purely CsvFs metadata/redirected access 5. SMB Connection Loss During Auto-pause SMB Client Connectivity on HV2 at auto-pause time: Event 30807: Share connection lost - "Le nom réseau a été supprimé" Event 30808: Share connection re-established What Has Been Done KB5075899 installed (Feb 21) — Maybe improved recovery from multi-cycle loop to single cycle a little, but did not prevent the auto-pause Disabled ms_server binding on iSCSI NICs (both nodes) Tuned MPIO: PathVerification Enabled, PDORemovePeriod 120, RetryCount 6, DiskTimeout 100 Drained HV2 — no effect Powered off HV2 — Completely eliminated the problem I'm currently running mad with this problem, i've deployed a lot of HyperV clusters and it's the first time i'm experiencing such a strange behavior, the only workaround i found is to take the second nodes off to be sure he is not putting locks on CSV files. The cluster is only running well with one node turned on. Why does the CsvFs driver on a non-coordinator node (HV2) maintain ~130 new SMB connections per hour to the CSV, even when it hosts no VMs and is drained?Why do these connections block for up to 24 hours during I/O peaks on the coordinator node? Why does draining the node not prevent CsvFs from accessing the CSV? Is this a known issue with the CsvFs driver in Windows Server 2025 Build 26100.32370? Are there any registry parameters to limit or disable CsvFs metadata scanning on non-coordinator nodes ? If someone sees somthing that i am missing i would be so grateful ! Have a great day.WAC can connect to itself or to other servers.
Hello, I have installed WAC with an internal certificate of my company. I can login to the web, the certificate appears correct in the browser. When I try to connect to the gateway itself or to other servers. No connection could be made because the target machine actively refused it: servergw.domain.com:6601 On event viewer: Event Winrest: Hosting failed to start Exception: System.InvalidOperationException: The requested certificate E=email address removed for privacy reasons could not be found in LocalMachine/My with AllowInvalid setting: False. The certificate is correct like other from company that used in other services, It has private key, and server authentication: E = email address removed for privacy reasons CN = email address removed for privacy reasons OU = company O = company bla bla L = City S = City C = Country I tried to create with other SAN: DNS=servergw.domain.com DNS=servergw DNS=localhost I have also tried to give permissions to the private key to Network Service, change the service to run with Local System. WinRM and trusted hosts are correctly. It only works when I install it with the self-signed certificate that WAC creates and it will say 60 days. What else can I try? Thanks !!
The file Microsoft_Server_InsiderPreview_LangPack_FOD_29531.iso is missing language packs.
Is it difficult to put these language packs in Microsoft_Server_InsiderPreview_LangPack_FOD_29531.iso? WinRe.wim PackageName PackageState ReleaseType InstallTime WinPE-DismCmdlets-Package~31bf3856ad364e35~amd64~~10.0.29531.1000 Installed FeaturePack 2/7/2026 15:07 WinPE-DismCmdlets-Package~31bf3856ad364e35~amd64~en-US~10.0.29531.1000 Installed LanguagePack 2/7/2026 15:07 WinPE-PlatformId-Package~31bf3856ad364e35~amd64~~10.0.29531.1000 Installed FeaturePack 2/7/2026 15:06 WinPE-PlatformId-Package~31bf3856ad364e35~amd64~en-US~10.0.29531.1000 Installed LanguagePack 2/7/2026 15:06 WinPE-PowerShell-Package~31bf3856ad364e35~amd64~~10.0.29531.1000 Installed FeaturePack 2/7/2026 15:07 WinPE-PowerShell-Package~31bf3856ad364e35~amd64~en-US~10.0.29531.1000 Installed LanguagePack 2/7/2026 15:07 WinPE-SecureBootCmdlets-Package~31bf3856ad364e35~amd64~~10.0.29531.1000 Installed FeaturePack 2/7/2026 15:07 WinPE-SecureBootCmdlets-Package~31bf3856ad364e35~amd64~en-US~10.0.29531.1000 Installed LanguagePack 2/7/2026 15:07 WinPE-UpdateOrchestrator-Package~31bf3856ad364e35~amd64~~10.0.29531.1000 Installed FeaturePack 2/7/2026 15:08 WinPE-UpdateOrchestrator-Package~31bf3856ad364e35~amd64~en-US~10.0.29531.1000 Installed LanguagePack 2/7/2026 15:09Can't download 29531
Hi can not download 29531 I get the below, I'm located in Sweden Error We are unable to complete your request at this time. Some users, entities and locations are banned from using this service. For this reason, leveraging anonymous or location hiding technologies when connecting to this service is not generally allowed. If you believe that you encountered this problem in error, please try again. If the problem persists you may contact Microsoft Support – page for assistance. Refer to message code 715-123130 and 2c3feb13-04f8-4432-bc28-c88fc015123b.Did Microsoft make a mistake? WinServer 2022 Standard and up.
Microsoft removed functionality of Windows Deployment Service. I know their are ways to to get around this but they either are hackjobs or deploying your own windows with PE. as far as i know of writing this. I know I could go linux. they have a simple cd to follow. Or Mac has their own version for macs. but not microsoft. They THREW it away for some stupid reason. Do I really have to do a VM or worse ditch DNS & DHCP?
Encrypted vhdx moved to new host, boots without pin or recovery key
Hyper-V environment. Enabled VTPM on guest Server, 2022 OS and encrypted OS drive C:\ with BitLocker. Host server 2022 has physical TPM. Shut down guest OS and copied vhdx file to another Hyper-V host server that is completely off network (also server 2022 with a physical TPM). Created a new VM based on the "encrypted" vhdx. I was able to start the VM without needing a PIN or a recovery key. Doesn't this defeat the whole point of encrypting vhd's? Searching says that this should not be possible, but I replicated it twice on two different off network Hyper-V host servers. Another odd thing is that when the guest boots on the new host and you log in, the drive is NOT encrypted. So, where's the security in that? Does anyone have any ideas on this or if I'm missing something completely? Or have I just made Microsoft angry for pointing out this glaring flaw??Modernized Gateway Extension Support via WAC SDK
Hello, I would like to build a gateway plugin for the latest WAC v2511 but according to this documentation, the latest SDK package does not support the latest modernized gateway extensions. Is there a way to workaround this without downgrading WAC version? https://learn.microsoft.com/en-us/windows-server/manage/windows-admin-center/extend/develop-gateway-plugin “The Windows Admin Center SDK and developer tools have not yet been updated to support development of gateway plug-ins compatible with the Windows Admin Center modernized gateway. Following this guide will not result in a .NET 8 extension compatible with the modernized gateway.
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