In case you didn't know Microsoft has fixed a known issue affecting Windows Server 2025 installations using iSCSI. This issue was causing 'boot device inaccessible' errors during startup.
Issue Details
The issue is around servers booting from an iSCSI LUN under NDIS Poll Mode. Microsoft first noted this the bug in late October 2024 and said it affected servers and these would encounter a boot error after completing the installation of Windows Server 2025.
What is iSCSI?
iSCSI or (Internet Small Computer Systems Interface) is a storage protocol that allows ones to connect to remote storage over TCP/IP. It allows it to use SCSI commands over IP networks. This allows remote storage on a storage area network (SAN) to appear as if it were a local disk. This type of storage is commonly used in virtualization, centralized storage, and data center environments.
Fix Released in February Updates
Microsoft has resolved the issue mentioned with the February 11, 2025 update (KB5051987).
🛠️ Solution: Microsoft recommends installing the latest cumulative update. It will include this fix along with other improvements.
Additional Fixes in KB5051987:
- Resolved USB audio and camera issues that occurred after the January 2025 security updates.
Other Windows Server 2025 Fixes
There are other fixes in recent updates as well:
✅ November 2024: Fixed bugs causing installation, upgrade failures, and BSODs on high-core count servers
✅ December 2024: Resolved boot failures on Windows Server 2022 with multiple NUMA nodes
Windows Server 2025 Availability
Windows Server 2025 (LTSC release) became generally available in early November. You can grab a copy to of Windows Server 2025 to play around with from the Microsoft Evaluation Center. This is a really great option for home labs and other test environments.
Important Takeaways
📌 If you're running Windows Server 2025 with iSCSI, make sure to install the KB5051987 update. This will help to make sure to prevent boot errors. Let me know if you have seen this issue? Let's discuss it.