Earlier this week, I reported that Microsoft had internally made the decision to hold the public release of Windows 10 Redstone 4, known as Version 1803, to the public due to a last minute blocking bug that was found over the weekend. At the time, I had assumed that Microsoft would be able to fix the issue via a patch, but it turns out things may not be that simple.
My sources are now suggesting that Microsoft has since demoted Windows 10 build 17133 from RTM status internally, meaning the company is now compiling new Redstone 4 builds once again in an attempt find a new one that passes the necessary criteria for public release. As a reminder, RTM stands for 'Release To Manufacturing' and is the build that goes out to partners for preloading onto new hardware, and is also the official build that gets rolled out to the world as an update.
What does this mean for you? If you're an Insider, not much. I'm told the bug isn't impactful enough to cause any real problems for Insiders on a day-to-day basis, but no source has been able to confirm to me what the bug actually is. Regardless, Microsoft will roll out another build via the Insider Program when it is ready to do so. For those that decided to upgrade to build 17133 outside of the Insider Program, you might still be in luck.
If you upgraded from the Fall Creators Update to Redstone 4, you may be able to revert back to the Fall Creators Update in just a couple of minutes by heading to Settings > Updates & Security > Recovery > Go back to the last build. This will revert you back the Fall Creators Update RTM, assuming that's what you upgraded from.
If you did a clean install of 17133 and don't want to join the Insider Program, things get a little trickier. It may turn out that the new RTM build will be made available as an update once it begins rolling out to the public in a few weeks, in which case you can just update to it then with no problems. You can also do an in-place upgrade to the new RTM once ISOs are made available, so not all is lost.
I believe each RTM candidate needs to be tested for a specific amount of time before Microsoft can deem it good enough for public consumption, which means the company is going to be cutting it incredibly close for an April release. We'll have to see what happens, and hopefully Microsoft is willing to give Insiders an explanation when it begins rolling out the next Redstone 4 build.
Microsoft demoting a build that it had internally deemed RTM is rather unprecedented. The company had already began preparing its systems for rollout of build 17133 to the public, but is now having to undo all that work in preparation for a new RTM build. Still, this is all in the name for a stable RTM build that the company strives to achieve and takes very seriously, so it's good Microsoft is going to all this effort to make sure that happens.
We'll keep you updated regarding the Windows 10 Redstone 4 release, but in the meantime let us know in the comments if you've already upgraded to 17133.