Microsoft has just released a couple of new Windows Insider builds for people on the fast ring, one for PC and one for mobile. The builds are surprisingly divergent.

For PC, the build is numbered 16176; it's another Redstone 3 build, though as with the first Redstone 3 build, it doesn't change a whole lot. It adds access to serial ports from the Windows Subsystem for Linux, which will help with remote device debugging. The build also fixes some minor bugs while introducing a new, less minor bug.

Specifically, if you use a Centennial application built using the Desktop Bridge—Microsoft's semi-virtualized technology for putting existing Win32 applications in the Windows Store—your system will crash. This will cause a Green Screen of Death—green, because a few builds back, Microsoft changed the screen color for Insider system crashes. At a glance, then, you can see the difference between a crashing machine on the stable Windows branch (as these remain blue) and a crashing machine on the developer branch.

That Microsoft is willing to put known system-crashing bugs into its main development branch and then ship that development branch to consumers (albeit consumers that have volunteered to test pre-releases) just underscores the importance of the company's guidance that nobody use the Insider builds for their daily driver PC. We continue to argue that this kind of thing undermines the value of the Insider program.

A few numbers can make a difference

For Mobile, the build is numbered 15204, and it is stamped as part of the "feature2" branch. This is something of an oddity. During the development of the Creators Update, the build numbers of Mobile and PC have remained largely the same, and their branch was named "rs2." Sometimes a build has gone out for one platform or the other (sometimes there's a PC bug that's irrelevant on Mobile, sometimes vice versa). But many of the builds have had the same number, denoting that they're built from the same version of the code.

But that now seems to have broken. The Creators Update for PC is build 15063, and that represents the final build of the Redstone 2 development branch. Subsequent builds of the Creators Update will update the patch version; at the time of writing, that's 138.

The Creators Update has not, however, shipped for the phone. It's due to arrive on April 25. Microsoft tells us that the 15204 mobile build is still a Creators Update build. This means that unlike the Anniversary Update, which was build 14393 for both PC and Mobile, the build numbers will be different for the Creators Update.

We expect that some time after the Creators Update ships for phones, some kind of realignment will occur. We've heard that there are Redstone 3 builds for mobile, but they're not ready for wide distribution just yet.

Update: Different people at Microsoft say that 15204 is in fact a post-Creators Update build, and that when the changes being made to the 16xxx branch have stabilized that the feature2 branch will go away, and PC and Mobile will once again be synchronized on redstone3. Creators Update for phones will be 15063, as it is for PCs.

The new Mobile build includes a new privacy settings screen that is shown after installation. This is the mobile counterpart to the new privacy settings seen in the desktop installation experience.

With this build, Microsoft is also confirming which phones will actually receive the final Creators Update. It's not a long list, and some beloved handsets such as the Lumia 1520 are omitted:

HP Elite x3

Microsoft Lumia 550

Microsoft Lumia 640/640XL

Microsoft Lumia 650

Microsoft Lumia 950/950 XL

Alcatel IDOL 4S

Alcatel OneTouch Fierce XL

SoftBank 503LV

VAIO Phone Biz

MouseComputer MADOSMA Q601

Trinity NuAns NEO

This same set of phones will also continue to receive new Insider builds after the Creators Update ships.