Microsoft has released cumulative update KB5102951 (build 28120.2387) for Windows 11 Insider Program participants on the Experimental channel. This build belongs to version 26H1 and contains a number of significant changes aimed at increasing interface customization flexibility, as well as special features for the education sector. The main focus of the build is on modernizing the taskbar, which now supports changing its screen position and a new compact display mode for devices with small displays. Additionally, insiders received fixes for issues related to File Explorer and the Outlook app.
- Taskbar position change. Users can now change the position of the taskbar on the screen. In Settings → Personalization → Taskbar → Taskbar behaviors, a choice of screen side is available: bottom, top, left, or right. In any position, tooltips, menus, and animations correctly appear from the side of the taskbar. Most appearance settings, including the smaller taskbar and Never combine taskbar buttons mode, work in all positions. Support for touch gestures, the search box, and the Ask Copilot feature in alternative positions is still being refined. Auto-hide taskbar and the tablet-optimized version are not yet supported.
- Smaller taskbar. The ability to use a smaller taskbar has been added to free up additional screen space, which is especially relevant for compact devices. In this mode, icons become smaller, and the height of the bar itself is reduced. Core elements such as Start, Search, and the notification area scale while maintaining alignment and a unified visual style. Size control is carried out via the Show smaller icons on the taskbar option in Settings → Personalization → Taskbar → Taskbar behaviors. When Always is selected, both the icons and the height of the bar are reduced. Work is underway to further simplify resizing in settings.
- Free upgrade to Windows 11 Pro for educational institutions (K-12). Insiders in K-12 educational environments can now upgrade from Windows 11 Home to the Windows 11 Pro for Education edition for free and in a one-way manner. This allows educational institutions to purchase devices with the Home version of the system and centrally update them for transfer to corporate management. To start the upgrade, you need to log in with a local account, run the command prompt as an administrator, execute the Clipupgrade.exe command and authorize with a K-12 organization account to confirm the upgrade right. The system will prepare the update and complete it after a restart. Reverting to Windows 11 Home without a clean reinstall is not supported.
As part of fixing known issues, Microsoft resolved an error that caused the OneDrive shortcut in File Explorer to stop functioning when launching the file manager with administrator privileges. Also fixed is an issue with the Outlook app, which last week might not have responded to pressing the close button. No other major documented issues have been identified in this build.
To install update KB5102951, you need to go to Settings → Windows Update and click the Check for updates button. The build will be downloaded and installed automatically; a computer restart is required to complete the process.
It should be remembered that this build is intended exclusively for Windows Insider Program participants on the Experimental channel of version 26H1 and contains changes that are still in the stage of active refinement, including incomplete support for touch gestures for alternative taskbar positions.
| Feature / Change | Performance Increase or Decrease | Optimization | PC Speed | Gaming Optimization |
|---|---|---|---|---|
| Taskbar position change | 🟡 Neutral to slight decrease (extra rendering for new layouts) | 🟢 UI flexibility optimized; animations correctly align to new edges | 🟡 Minimal overhead during position switching, otherwise negligible | ⚪ No direct impact; touch/auto-hide refinements pending |
| Smaller taskbar | 🟢 Slight increase (reduced GPU/compositing load for smaller elements) | 🟢 Screen real estate reclaim optimized; icon and height scaling streamlined | 🟡 Marginal gain on compact/low-resolution devices | ⚪ Not applicable |
| Free upgrade to Windows 11 Pro for Education (K-12) | ⚪ No impact (licensing change only) | 🟢 Deployment workflow optimized for institutional IT | ⚪ No measurable change | ⚪ Not applicable |
| OneDrive shortcut fix (admin-privilege File Explorer) | 🟢 Slight increase (eliminates hung/blocked UI thread) | 🟢 Shell extension reliability optimized | 🟡 Faster file-manager response in elevated sessions | ⚪ No direct impact |
| Outlook close-button unresponsiveness fix | 🟢 Slight increase (prevents resource leak from unclosed window) | 🟢 UI message-loop responsiveness optimized | 🟡 Minor improvement when Outlook runs alongside other apps | ⚪ No direct impact |
Find and Change Settings
| Setting | Where to find | How to change |
|---|---|---|
| Taskbar Position | Settings → Personalization → Taskbar → Taskbar behaviors | Open Settings, go to Personalization, then Taskbar, and expand Taskbar behaviors. Use the dropdown menu to choose the taskbar location on screen: Bottom, Top, Left, or Right. Tooltips, menus, and animations will adjust to the selected side automatically. |
| Smaller Taskbar | Settings → Personalization → Taskbar → Taskbar behaviors | Go to Settings, then Personalization, select Taskbar, and expand Taskbar behaviors. Find the "Show smaller icons on the taskbar" option and set it to Always to reduce icon size and taskbar height. To revert to the default size, turn the option off. |
| Free Upgrade to Windows 11 Pro for Education (K-12) | Command Prompt (Administrator) | Log in with a local account, open Command Prompt as administrator, run the Clipupgrade.exe command, and authenticate with a K-12 organization account to confirm upgrade rights. The system will prepare the update and complete it after a restart. Reverting to Windows 11 Home requires a clean reinstall. |
Official announcement on the Microsoft website.
The last 10 Windows updates:
| Update | Build | Version | Windows | Channel | Date |
|---|---|---|---|---|---|
| KB5121132 | 28120.2760 | 26H1 | Windows 11 | Experimental | 2026-08-21 |
| KB5124040 | 26220.9223 | 25H2 | Windows 11 | Beta | 2026-08-21 |
| KB5124042 | 26340.9233 | 26H2 | Windows 11 | Experimental | 2026-08-21 |
| KB5121106 | 28020.2731 | 26H1 | Windows 11 | Beta | 2026-08-17 |
| KB5121109 | 28120.2738 | 26H1 | Windows 11 | Experimental | 2026-08-17 |
| KB5124036 | 26220.9202 | 25H2 | Windows 11 | Beta | 2026-08-17 |
| KB5124038 | 26340.9212 | 26H2 | Windows 11 | Experimental | 2026-08-17 |
| KB5120996 | 28000.2796 | 26H1 | Windows 11 | Preview | 2026-08-14 |
| KB5120998 | 26200.9267 | 25H2 | Windows 11 | Preview | 2026-08-14 |
| KB5120240 | 22631.7517 | 23H2 | Windows 11 | Stable | 2026-08-11 |