Microsoft has released cumulative update KB5124163 (Build 28020.3112) for Windows 11, version 26H1, for Insiders in the Beta Channel. The update includes a small set of general improvements and fixes that make the system more stable. Among the individual fixes, one is listed in the release notes – in Hyper-V. The changes are rolling out gradually among Insiders, so they will not appear for everyone at the same time.
- Hyper-V. Fixed an issue where apps with virtual machines managed by the Host Compute Service (HCS) could not work with host shared folders via Plan9: folders opened from a Windows PC did not appear in the Linux guest system or became unavailable.
Installation via Windows Update: go to Settings > Windows Update and click Check for updates. A restart of the computer will be required to complete the installation.
| Feature / Change | Performance Increase or Decrease | Optimization | PC Operation Speed | Gaming Optimization |
|---|---|---|---|---|
| Hyper-V – Fixed an issue where apps with virtual machines managed by the Host Compute Service (HCS) could not work with host shared folders via Plan9: folders opened from a Windows PC did not appear in the Linux guest system or became unavailable | 🟡 Neutral (~0%) | 🟢 Plan9 host shared folder handling optimized | ⚪ No measurable impact | ⚪ No impact |
Find and Change Settings
| Setting | Where to find | How to change |
|---|---|---|
| Hyper-V Host Shared Folders via Plan9 for HCS-managed virtual machines |
Settings > System > Optional features > More Windows features > Hyper-V Hyper-V Manager > Virtual Machines > Settings > Integration Services Hyper-V Manager > Virtual Machines > Settings > Management > Shared Folders (Plan9) |
This update fixes an issue where apps with virtual machines managed by the Host Compute Service (HCS) could not work with host shared folders via Plan9, causing folders opened from a Windows PC to not appear in the Linux guest system or become unavailable. To use shared folders, open Hyper-V Manager, select your virtual machine, go to Settings > Integration Services and enable "Guest services" and the Plan9 share provider. Then go to Settings > Management > Shared Folders and add the host folder you want to expose. Inside the Linux guest, mount the Plan9 share (for example with mount -t 9p) so the folder becomes visible and available. No manual change is required for the fix itself; it is applied automatically once the update is installed. |
Official announcement on the Microsoft website.
The last 10 Windows updates:
| Update | Build | Version | Windows | Channel | Date |
|---|---|---|---|---|---|
| KB5124166 | 26220.9568 | 25H2 | Windows 11 | Beta | 2026-09-25 |
| KB5124163 | 28020.3112 | 26H1 | Windows 11 | Beta | 2026-09-25 |
| KB5124162 | 28120.3122 | 26H1 | Windows 11 | Experimental | 2026-09-25 |
| KB5124165 | 26340.9577 | 26H2 | Windows 11 | Experimental | 2026-09-25 |
| KB5124006 | 28000.3086 | 26H1 | Windows 11 | Preview | 2026-09-22 |
| KB5124010 | 26200.9550 | 26H2 | Windows 11 | Preview | 2026-09-22 |
| KB5124138 | 28120.3032 | 26H1 | Windows 11 | Experimental | 2026-09-18 |
| KB5124140 | 26220.9492 | 25H2 | Windows 11 | Beta | 2026-09-18 |
| KB5124137 | 26340.9502 | 26H2 | Windows 11 | Experimental | 2026-09-18 |
| KB5129242 | 22631.7584 | 23H2 | Windows 11 | Stable | 2026-09-14 |