Skip to the content
The Update Bureau
Windows 11 Windows 11 Insider Future platforms Insider Preview, Experimental Channel
Windows Insider

Build 29671.1000

Build 29671.1000: Windows Insider Experimental Channel, September 2026. Hyper-V folder sharing and UAC freeze fixes

In short

Fixes Linux VM folder sharing and freezes triggered by UAC prompts. The notes also list unresolved performance and VMware issues.

Does it affect you? Applies to: Devices enrolled in the Windows Insider Program in the Experimental Channel.

Build
29671.1000
Review notes Additional details from the official release notes (1) Read note
  • In short The fix addresses a folder-sharing problem affecting some applications using HCS-managed virtual machines and Plan9 with Linux VMs.

The official sources are linked at the end of the page.

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

Fixes 2 changes

Hyper-V

Gradual rollout
  • Folders shared from the Windows host can appear and be accessed in Linux virtual machines using Plan9.1
    Fixes folder sharing for some applications using HCS-managed virtual machines and Plan9.

Other

Gradual rollout
  • Some Insiders' PCs no longer freeze when a UAC prompt appears.2

Removal 1 change

Start menu customization

For: Experimental Channel Insiders

  • The Start menu customization improvements were removed from this channel's release notes. Microsoft says it plans to bring them in a future update.3

Technical details

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

Data sheet

Released
2026-09-18
Type
Windows Insider build
VersionBuildChannel
— 29671.1000 Experimental Channel

Security

No vulnerabilities are listed for this update.

Sources

Updated
Cited passages from Microsoft's official notes (3)
  1. 1. Fixed an issue where some applications that used HCS-managed virtual machines experienced issues when sharing host folders with Linux VMs using Plan9. Folders shared from the Windows host using Plan9 didn't appear or couldn't be accessed in the guest environment. learn.microsoft.com
  2. 2. Fixed an issue causing some Insiders to have their PC freeze when the UAC prompt appeared in recent flights. learn.microsoft.com
  3. 3. [Update 25 September 2026: Removal of the Start menu customisation improvements from release notes for this channel. We look forward to bringing these imporvements in a future update] learn.microsoft.com
Checked automatically: 8 of 8 checks passed, 3 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 4/5, clarity 3/5, completeness 4/5. 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