Microsoft’s unprecedented bungling of the final release of Windows 10 version 1803 has an interesting side-effect. So if you used my tip to upgrade to this release during the so-called “magic window” period, you got some work to do.

To recap, Microsoft originally intended for build 17133.1 to be the final release of Windows 10 version 1803. And the firm originally intended to start the staged public release of this version, via the “Redstone 4” feature update, last Tuesday.

That didn’t happen. And while Microsoft was awfully quiet about what went wrong for the past week, it finally opened up today with the release of build 17134.1, which is the new “RTM” build of Windows 10 version 1803.

“Windows 10 Insider Preview Build 17134 (RS4) has no new features and includes the fixes from KB4100375 as well as some fixes for general reliability of the OS,” Microsoft’s Dona Sarkar explained. “As Build 17133 progressed through the rings, we discovered some reliability issues we wanted to fix. In certain cases, these reliability issues could have led to a higher percentage of (BSOD) on PCs for example. Instead of creating a Cumulative Update package to service these issues, we decided to create a new build with the fixes included.”

Historically, Microsoft has fixed post-RTM issues via cumulative updates, so it’s unclear why they needed to halt the rollout of this release in order to create a new RTM build. But they did.

And that has ramifications for anyone who upgraded to what was originally the RTM build of Windows 10 version 1803 using my tip. Yes, build 17134 will quickly make its way down through the Insider rings system, hitting the Slow and Release Preview rings over the next few days. But if you want to upgrade to the new RTM build now, you’ll need to go through the “magic window” trick again.

Which goes like this.

• Open Settings and navigate to Update & Security > Windows Insider Program.
• Click Get Started to begin the process of enrolling your PC back into the Insider Program.
• Sign-in to your Microsoft account as directed and choose “Active development of Windows” and then “Fast” as you step through the wizard. Reboot when requested.
• After you reboot and sign-in, open Settings, navigate to Update & Security, and click “Check for updates.” Windows 10 build 17134.1 will download and install.
• After the new build is installed and the PC is upgraded, you can unenroll the PC from the Windows Insider program using the steps provided in Tip: The Magic Window for Windows 10 RS4 is Here.

Because the magic window is here. Again.