Windows 10 build 20277 hits Dev channel Insiders as testing splits

What you need to know

• Windows 10 build 20277 is now available for Dev channel testers.
• This is one of two new builds released today as the Dev channel splits in two.
• 20277 will land for everyone automatically, but "seekers" can get 21277 instead.

Windows 10 build 20277 is now available for Dev channel Insiders to test and, if you're paying attention, you may notice that's the second build to roll out to the Dev channel today. That's because Microsoft has, at least temporarily, split the Dev channel in two. Here's a look at what's going on.

Starting today, Microsoft is giving Dev channel Insiders the option to start testing builds from the RS_PRERELEASE branch, which is where build 21277 comes in. You have to opt in to testing from this branch, and you'll continue to receive builds from RS_PRERELEASE going forward if you do.

If you decide not to opt in, you'll stay testing builds from the FE_PRERELEASE branch, which receives build 20277 today. This is the build that will automatically go out to Dev channel Insiders today unless they opt in to jump on the RS_PRERELEASE branch. In terms of changes, 20277 is much less ambitious, containing just a couple of fixes.

Looking forward, Microsoft says it plans to merge all Dev channel testers to RS_PRERELEASE at some point after the holidays. For now, here's a look at what's in the 20277 release notes.

What's new in Windows 10 build 20277

Fixes

• We fixed an issue that could result in the WinRE volume label being lost after multiple upgrades.
• We fixed an issue that could result in apps failing to update with error code 0x80073D02.

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.

If you're already on the Dev channel, you'll get 20277 via Windows Update automatically. If you'd rather switch to testing 21277, it's available as a "seeker" experience in Windows Update, meaning you'll have to manually choose to install it.