A month and a half ago, Microsoft released a preview update to Build 19035 for Windows Insider Preview. Today Microsoft released the Build 19551 update, which is notable for its first post-2004 branch release, which is the first preview update for the next major release. Interestingly, the actual RTM version of Windows 10 Version 2004 is Build 19041, and Windows Server Insiders won’t see these previews. On the server side, internal staff will only test vNext.
It’s not clear what’s new in the build, as Microsoft hasn’t actually released any release notes. This is normal for the new Server version, and while it’s not clear why Microsoft can’t put the release time with the blog post together, it might eventually publish something. What we do know is that vNext is no longer bound to a specific version of Windows, which is a new method for Insider testing. Microsoft will start rolling out new features on the market, and on the client side, it will eventually be split into a Slow ring for release.
Update: Build 19551 Official Blog Has Been Updated
According to the official blog, the new version has released a patch that allows National Language Support (NLS) components to be container-aware. Each container will now instantiate the NLS state. The patch also fixes situations where some container OS components are trying to access what is not available in the container because of instantiation.