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Windows 11 Windows 11 Insider 26H2 Insider Preview, Experimental Channel
Windows Insider

Build 26300.8758

Build 26300.8758: Windows Insider Experimental Channel, June 2026. Taskbar size controls and File Explorer fixes

In short

Adds a dedicated taskbar size setting, refines taskbar transitions, improves File Explorer previews and details, and fixes two File Explorer issues.

Does it affect you? Applies to: Windows Insiders in the Experimental Channel. This build is based on Windows 11, version 26H2.

Build
26300.8758

This is a test build for people in the Windows Insider Program. Features in it can change, be removed, or never reach regular Windows releases.

What changes

Improvements 4 changes

Taskbar

Gradual rollout

For: Insiders in the Experimental Channel

  • Transitions between taskbar sizes are smoother.1

File Explorer

Gradual rollout 2 items

For: Insiders in the Experimental Channel

  • Thumbnail previews for cloud files are more reliable in the Details pane.2
  • File properties are easier to find and review at a glance in the reorganized Details pane.3

Sounds

Gradual rollout

For: Insiders in the Experimental Channel

  • System sounds are improved when Windows is in dark mode.4

Fixes 2 changes

File Explorer

Gradual rollout 2 items

For: Insiders in the Experimental Channel

  • The OneDrive shortcut works when File Explorer runs as administrator.5
  • The confirmation dialog for permanently deleting a file shows the original file name instead of an internal Recycle Bin file name.6

New feature 1 change

Taskbar

Gradual rollout

For: Insiders in the Experimental Channel

  • A dedicated Taskbar Size setting makes it easier to find and choose a taskbar size.7

Technical details

Data sheet · Security · Downloads · Components Click to collapse or expand

Data sheet

Released
2026-06-26
Type
Windows Insider build
VersionBuildChannel
26H2 26300.8758 Experimental Channel

Security

No vulnerabilities are listed for this update.

Sources

Updated
Cited passages from Microsoft's official notes (7)
  1. 1. We've also made refinements to the transitions between taskbar sizes for a smoother overall experience. learn.microsoft.com
  2. 2. We've improved the reliability of thumbnail previews for cloud files in the Details pane. learn.microsoft.com
  3. 3. The pane has also been reorganized so file properties are easier to find and review at a glance. learn.microsoft.com
  4. 4. Improved system sounds when using Windows in dark mode. learn.microsoft.com
  5. 5. Fixed an issue where the OneDrive shortcut in File Explorer stops working when File Explorer is run in administrative mode. learn.microsoft.com
  6. 6. Fixed an issue where the confirmation dialog might display an internal Recycle Bin file name instead of the original file name when permanently deleting a file. learn.microsoft.com
  7. 7. Taskbar customization just got easier. As we continue to make improvements to the Taskbar experience mentioned last month, we've introduced a dedicated Taskbar Size setting, making it simpler to find, understand, and personalize your ideal taskbar experience. learn.microsoft.com
Checked automatically: 8 of 8 checks passed, 7 quoted passages
  • Quotes found in the official pages: passed
  • Numbers found in the sources: passed
  • Vulnerabilities from the dossier only: passed
  • Links to allowed domains only: passed
  • Every official change covered: passed
  • Readable plain text: passed
  • Changes confirmed by the file list: passed
  • Sources agree: passed

A second AI read the text against the sources: correctness 5/5, clarity 5/5, completeness 5/5. How we work

Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake