Microsoft has released cumulative update KB5124138 (Build 28120.3032) for Windows 11, version 26H1 for Insiders in the Experimental channel.
- Windows recovery. Cloud Rebuild is a recovery option that returns a Windows 11 PC to a clean, known-good state by fully reinstalling the system, even if Windows will not boot. Unlike the Reset this PC feature, Cloud Rebuild downloads both the Windows image and device drivers from Windows Update, so the PC returns to a fully working state without a USB drive, without your own image, and without depending on the health of the already installed system.
- Recovery starts directly from the Windows Recovery Environment (WinRE). Troubleshoot > Recovery and removal > Cloud Rebuild.
- The internet connection is configured in the same place — via Ethernet cable or Wi-Fi network.
- Before starting, you need to check the target Windows build, edition, and language, and then confirm the data loss warning.
- Hyper-V. Fixed a bug where applications with virtual machines managed by the Host Compute Service (HCS) could not work with host shared folders via Plan9: folders opened from a Windows computer did not appear in the Linux guest system or were unavailable.
Known issues: The bug where Easy Anti-Cheat (EAC) would not start and showed the message The application was unable to start correctly (0xc000007b) is marked as resolved in Microsoft's release notes.
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/Decrease | Optimization | PC Speed | Gaming Optimization |
|---|---|---|---|---|
| Cloud Rebuild recovery (full reinstall from WinRE, image and drivers downloaded from Windows Update) | 🟢 High increase (recovers to a clean known-good state even when Windows will not boot; no USB drive, no custom image, no dependency on the health of the installed system) | 🟢 High (eliminates manual media preparation and driver hunting; returns PC to a fully working state) | 🟢 High (clean install removes accumulated corruption, bloat and broken states, restoring baseline system responsiveness) | 🟡 Medium (indirect — a clean system restores gaming performance to baseline, but no game-specific tuning) |
| Cloud Rebuild network setup in WinRE (Ethernet or Wi-Fi configured in the same place) | ⚪ No direct performance impact | 🟢 Medium (removes the need for external media and a second working PC to obtain a network driver) | ⚪ No impact | ⚪ No impact |
| Cloud Rebuild pre-checks (target build, edition, language verification and data loss warning) | ⚪ No performance impact | 🟡 Medium (prevents wrong-edition/language reinstalls and reduces failed recovery attempts) | ⚪ No impact | ⚪ No impact |
| Hyper-V fix: HCS-managed VM apps now work with host shared folders via Plan9 | 🟢 High increase (host shared folders previously did not appear or were unavailable in the Linux guest) | 🟢 High (restores intended host-guest file sharing workflow without workarounds) | 🟡 Medium (removes stalls and failed folder mounts in VM workflows) | ⚪ No impact |
Find and Change Settings
| Setting | Where to find | How to change |
|---|---|---|
| Cloud Rebuild | Windows Recovery Environment (WinRE) > Troubleshoot > Recovery and removal > Cloud Rebuild | Start recovery directly from the Windows Recovery Environment (WinRE) by going to Troubleshoot > Recovery and removal > Cloud Rebuild. Configure the internet connection in the same place, using an Ethernet cable or a Wi-Fi network. Before starting, check the target Windows build, edition, and language, then confirm the data loss warning. Cloud Rebuild downloads both the Windows image and device drivers from Windows Update, so no USB drive and no own image are required. |
Official announcement on the Microsoft website.
The last 10 Windows updates:
| Update | Build | Version | Windows | Channel | Date |
|---|---|---|---|---|---|
| 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 |
| KB5129236 | 19045.7727 | 22H2 | Windows 10 | Stable | 2026-09-14 |
| KB5129195 | 26300.9457 | 26H2 | Windows 11 | Stable | 2026-09-14 |
| KB5129194 | 28000.2956 | 26H1 | Windows 11 | Stable | 2026-09-14 |
| KB5124115 | 26220.9472 | 25H2 | Windows 11 | Beta | 2026-09-11 |