Microsoft today released two new Windows 10 previews for PCs, the first time it’s done so in 2019. The first build is from the 19H1 branch, which represents the Windows 10 update that will arrive in the first half of this year, and the second is from the 20H1 branch, which will arrive in the first half of 2020.

Microsoft has released two new builds on the same day before, but never for two updates that are so far apart. The company is simply more comfortable developing multiple major Windows 10 updates at once.

Windows 10 is being developed as a service, meaning it receives new features on a regular basis. Microsoft has released six major updates so far: November Update, Anniversary Update, Creators Update, Fall Creators Update, April 2018 Update, and October 2018 Update.

Windows 10 build 18343

This 19H1 build includes the following general bug fixes and improvements:

  • Fixed the Connected Standby issue that resulted in us blocking PCs with Intel64 Family 6 Model 142 and Intel64 Family 6 Model 158 processor model. If your PC was unable to take Build 18342 from earlier this week due to having one of these processor models, you should be able to take this flight.
  • Fixed the issue that required an additional reboot when performing Reset this PC and selecting Keep my files on a device that has Reserved Storage enabled.

In the 19H1 branch, this update bumps Windows 10 from to build 18342 (made available to testers on February 20) to build 18343.

This build has eight known issues:

  • Launching games that use anti-cheat software may trigger a bugcheck (GSOD).
  • Creative X-Fi sound cards are not functioning properly.
  • Issues in the night light space.
  • Some Realtek SD card readers are not functioning properly.
  • In Windows Sandbox, if you try to navigate to the Narrator settings, Settings app crashes.
  • Mouse pointer color might be incorrectly switched to white after signing out and signing back in.
  • The Chinese version of multiple games are not working.
  • If you install any of the recent builds from the Fast ring and switch to the Slow ring – optional content such as enabling developer mode will fail. You will have to remain in the Fast ring to add/install/enable optional content. This is because optional content will only install on builds approved for specific rings.

Windows 10 build 18841

This build is for Windows Insiders who have chosen the Skip Ahead option, which only a small subset of Insiders can opt into. Normally, that would have meant 19H2 builds, since 19H1 hasn’t been released yet, but Microsoft has chosen to really skip ahead this time around.

This 20H1 build includes the following general bug fixes and improvements:

  • Windows Sandbox now supports configuration files! These files allow users to configure some aspects of the sandbox, such as vGPU, networking and shared folders. A blog post to explain this new feature is available here.
  • Windows Sandbox now captures hotkeys in full screen.
  • Fixed an issue where Windows Sandbox would not start on localized builds.
  • Improved error reporting in Windows Sandbox. Now the error dialog includes the error code and a link to the Feedback Hub.
  • Fixed an issue where Windows Sandbox was unexpectedly throwing an error due to referencing a deleted file under Windows.old.
  • Fixed an issue where if you unpinned groups from Start, apps might end up thinking their tiles were still pinned.
  • Fixed a recent issue where if you hid the search icon in the taskbar, a number of win32 apps would unexpectedly redraw when opening the Start menu.
  • Fixed an issue resulting in the Search pane becoming truncated if launched after rotating the device orientation from horizontal to vertical.
  • Fixed an issue where Settings would sometimes crash when opening “Advanced Display Settings” from Display Settings.
  • Fixed an issue where it wasn’t possible to add a drive to the list of folders to exclude when setting up Enhanced Search in Settings.
  • Fixed an issue where there were unexpected characters in the text under the Storage Sense listing for temporary files.
  • Fixed an issue resulting in certain games no longer rendering UI updates (appearing visually stuck) after using Alt + Tab to quickly switch away and back to the game.
  • Fixed an issue resulting in the taskbar blinking if an AC adapter was attached when the device had less than 20% battery.
  • Fixed an issue resulting in the taskbar disappearing for a second when dismissing Start/Cortana/Search on a secondary monitor.
  • Fixed an issue resulting in File Explorer potentially hanging when trying to rename, delete, or move MKV files in the recent flights.
  • Fixed an issue that could cause Windows logon to forget the last logged on user, and instead would display the sign-in prompt for the default user from the list after dismissing the lock screen.
  • Fixed an issue resulting in CDPUserSVC using an unexpectedly large amount of CPU for prolonged periods of time.
  • Fixed an issue where the newly added popup window shadows might unexpectedly stop appearing after using your PC for some time.
  • Fixed an issue impacting UWP apps resulting in entries under a “…” that launched other apps not working after the first time the secondary app was launched.
  • Fixed an issue resulting in the left and right arrows on the touch keyboard inserting 4 and 6, respectively, in certain languages.
  • Fixed an issue resulting in the game bar record and broadcast options unexpectedly not working in recent builds.
  • Fixed an issue impacting Emoji Panel and Clipboard History reliability.
  • Fixed an issue in Ease of Access’s Cursor and pointer settings, mouse pointer size and color are now retained on upgrade. There is a remaining issue with mouse pointer showing white color instead of the selected color after signing out and signing back in.
  • When using the Magnifier with larger pointers, it pans smoothly as the pointers change shape.
  • Fixed an issue where navigation mode on Orbit braille display could not be changed.
  • Fixed an issue where Narrator paused unexpectedly when reading through a PDF.
  • Fixed the issue that required an additional reboot when performing Reset this PC and selecting Keep my files on a device that has Reserved Storage enabled.

In the 20H1 branch, this update bumps the Windows 10 build number for PCs from build 18836 (made available to testers on February 14) to build 18841.

This build has eight known issues:

  • Launching games that use anti-cheat software may trigger a bugcheck (GSOD).
  • Night light reliability continues to have issues.
  • Some Realtek SD card readers are not functioning properly.
  • In Windows Sandbox, if you try to navigate to the Narrator settings, Settings app crashes.
  • Mouse pointer color might be incorrectly switched to white after signing out and signing back in.
  • Creative X-Fi sound cards are not functioning properly.
  • You may experience an increase in Start menu reliability issues on this build — a fix will be included in the next flight.
  • If you install any of the recent builds from the Skip Ahead and switch to either the Fast ring or the Slow ring – optional content such as enabling developer mode will fail. You will have to remain in the Fast ring to add/install/enable optional content. This is because optional content will only install on builds approved for specific rings.

Don’t install either build on your production machine.