HomeWinBuzzer NewsWindows 10 21H1 Preview 20251 Arrives but Without Features

Windows 10 21H1 Preview 20251 Arrives but Without Features

Insiders can now test Windows 10 21H1 build 20251, but the release highlights Microsoft’s changing of the Dev channel.


is rolling out Windows 10 Insider Preview Build 20251. Before Insiders rub their hands with glee at the prospect of new features, it's worth pointing out there aren't any. Instead, this update reflects how Microsoft has changed the Insider Program.

These days, the Dev channel is the release branch for preview instead of prerelease. As is customary, there are no new features in release branch updates. That because traditionally this branch has been for updates that are just about to roll out to all users. In other words, it was feature complete and ready to leave preview.

That's no longer the case. These days, Microsoft also uses the release branch (Dev channel) for a dummy version of a feature update. This is the company's way to ensure the base of the update is good.

While Insider Preview Build 20251 is a preview, it is not how the final release for next year's feature update will look. There will be new preview features coming to other Insider branches before.

Microsoft has for some reason changed the remit of the Dev channel. When announced as part of a Windows Insider Program overhaul this year, Microsoft said the Dev channel would be a permanent rs_prerelease branch. That meant it would be a branch where Insiders could access builds directly before they launch… that is no longer the case.

Either way, Windows 10 Insider Preview Build 20251 is available now with the following changes.

Release Notes


  • We fixed an issue resulting in the background of some dialogs to unexpectedly appear grey instead of white in the last couple flights.
  • We fixed an issue resulting in the taskbar occluding the Power button in the Start menu for some Insiders recently.
  • We fixed an issue resulting in some Insiders seeing a SYSTEM THREAD EXCEPTION NOT HANDLED bug check.
  • We fixed a crash with opengl32.dll.
  • We fixed an issue that could result in the Settings app hanging when checking for updates right after upgrade.
  • We fixed an issue that could result in the Settings app sending a notification that just said “new notification”.
  • We fixed an issue resulting in the Search Indexer not being able to retrieve metadata from HEIF and WebP files, so you couldn't search for those files using metadata like date taken.
  • We fixed an issue resulting in the Cast to Device option in Movies & TV (and other playback apps) not taking any action when clicking on a listed device in recent builds.
  • We fixed an issue in recent builds that could result in the screen you were projecting with Miracast freezing shortly after connecting.
  • [UPDATE] We fixed the issue causing Windows PowerShell to fail to launch for Insiders on ARM PCs such as the Surface Pro X .

Known issues

  • We're working on a fix for an issue starting with Build 20236 where installing games from the Store to a secondary non-OS drive will result in the secondary drive becoming inaccessible. To prevent this from occurring you must change the default storage for new content to the secondary drive PRIOR to installing the game. This can be done in Settings > Storage > Change where new content is saved.
  • We're looking into reports of the update process hanging for extended periods of time when attempting to install a new build.
  • Live previews for pinned sites aren't enabled for all Insiders yet, so you may see a grey window when hovering over the thumbnail in the taskbar. We're continuing to work on polishing this experience.
  • We're working on enabling the new taskbar experience for existing pinned sites. In the meantime, you can unpin the site from the taskbar, remove it from the edge://apps page, and then re-pin the site.
  • We're working on a fix for an issue causing some devices to experience a DPC_WATCHDOG_VIOLATION bugcheck.
  • We're investigating reports that some users are seeing error 0x80070426 when using their Microsoft account to sign into various apps. If you encounter it, rebooting your PC may resolve this.
  • [ADDED] We're investigating an issue where, after taking this build, no drives appear under Settings > System > Storage > Manage Disks and Volumes. As a workaround, you can manage your disks in the classic Disk Management tool.
Luke Jones
Luke Jones
Luke has been writing about all things tech for more than five years. He is following Microsoft closely to bring you the latest news about Windows, Office, Azure, Skype, HoloLens and all the rest of their products.

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