Microsoft releases final Windows 10 'Iron' build to Insiders in the Dev Channel

Windows Update
Windows Update (Image credit: Windows Central)

What you need to know

  • Build 20279 is now available in the Dev Channel.
  • It's the last fe_release build Insiders will need to test.
  • It has no fixes or changes, just known issues.

Microsoft has released a new build to Insiders in the Dev Channel this week, and it's likely to be the last from the "Iron" fe_release branch that has had very little in it in the last few weeks. For those unaware, "Iron" is the codename for the 21H1 release of Windows, but it won't be coming to Windows 10 desktop. It's a release for Windows 10X and Windows Server 2021 only.

That's why the fe_release builds have essentially had nothing in them, because all the work going on for Windows 10 Iron releases is happening on entirely different versions of the OS. Microsoft is finalizing Windows 10X (and ultimately, the Iron codebase) with build 20279, so they've been pumping out bug fixes and changes big time internally, but none of that really translates to the desktop builds.

Windows 10 desktop will get its own 21H1 release, but it won't be based on the Iron codebase. Instead, 21H1 for desktop will be based on the Vibranium codebase (version 2004) just like the 20H2 update released a few weeks ago. Windows 10 desktop's next big feature update will ship in the fall of 2021 with version 21H2, as part of the Cobalt codebase which is in development now.

For some reason, Microsoft doesn't think it needs to communicate this kind of thing with Insiders, but I think they do. I think it's important for Insiders to know what they're testing, and why they're testing it. Microsoft's official reasoning for releasing these builds is that they are simply testing to see if they can release two builds in quick succession. While that may be true in part, it's not the full story.

Hopefully Microsoft decides to be more open with Insiders in 2021. I don't know why they like to play secretive when it comes to this sort of thing. They rarely talk about Windows development branches, semesters, or schedules for these things, and I really think they should as it's all vital information to the Insiders who are testing these builds.

Either way, here's the changelog for today's fe_release build on desktop. There are no fixes or changes, just known issues:

  • 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 resulting in some users seeing error 0x80070426 when using their Microsoft account to sign into various apps. If you encounter it, rebooting your PC may resolve this.
  • We're working on a fix for an issue where, in recent Dev Channel builds, 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.

It's worth noting that Microsoft can roll another RTM build if it finds a last minute showstopper bug. So while 20279 is considered the Final Build for now, it won't be locked in until after the holiday's. The build is available in the Dev Channel for those who didn't update to the rs_prerelease build 21277 released last week.

Zac Bowden
Senior Editor

Zac Bowden is a Senior Editor at Windows Central. Bringing you exclusive coverage into the world of Windows 10 on PCs, tablets, phones, and more. Also an avid collector of rare Microsoft prototype devices! Keep in touch on Twitter: @zacbowden.

  • I agree with the sentiment of this article. What's all this secrecy for? There is no harm in people knowing these things, not even if they eventually change their minds for some reason.
  • "That's why the fe_release builds have essentially had nothing in them, because all the work going on for Windows 10 Iron releases is happening on entirely different versions of the OS." The very first emulator build of Windows 10X had an updated settings app with rounded corners and a more current design. What's the reason they couldn't port that over to Insider builds?
  • I don't see the point to be in the Dev channel anymore. Let's test something that we might not get? What is the point in this? It is not helping any individual, organisation, business or enterprise testing what might not be coming.
    We definitely need some clarification from Microsoft. I'm no longer testing.
  • Testing features that may or may not be implemented is the point of these builds. They take the user feedback and whatever diagnostics data to decide how well it works, how much it's used and how practical a feature is or isn't for the average or business consumers. A feature may seem like a good idea on paper, but when implemented, it may not be practical, useful or disrupts the flow of things to use it. Just my thoughts on it.
  • rs_prerelease build 21277 is available for insiders in the Dev channel.
  • When I read the word "Iron" in the title before clicking on the article. I immediately thought of Marv in Home Alone (One) getting hit in the face with the flat side of an Iron after he pulls what he thinks is a light switch. After reading the article it felt like an apt metaphor lol....
  • I hope next time the windows central team can provide a little chart with all the codenames, branches an timeframes.