Direct MSU download links
Download and install these MSUs in this order, reboot after each one:
(Updates with a * aren’t part of the Spring Update according to the leaked ADK, but they do show up after the registry hack. Install them, or don’t, it’s up to you…)
(I added ARM downloard for Windows RT, but WiFi drivers might not work correctly, please be careful!)
KB2919442: 32-Bit – 64-Bit – ARM
*KB2939087: 32-Bit – 64-Bit – ARM
KB2919355: 32-Bit – 64-Bit – ARM
KB2932046: 32-Bit – 64-Bit – ARM
*KB2938439: 32-Bit – 64-Bit – ARM
KB2937592: 32-Bit – 64-Bit – ARM
Thanks to Arseny92 from MDL for explaining how to get these links and thanks to many other users for actually posting them!
How is this even possible??
Nobody knows for sure, but I think the registry key is an internal flag used by Microsoft employees who are “dogfeeding” (updating as soon as a new build is available for testing, almost every day) the Windows 8.1 Update. When they enable this key Windows Update will search for updates on an internal, confidential, update server, that way they will easily get the latest updates for testing and they can test if updating works properly. Another possibility is that this key was created to specifically test 8.1.1 RTM deployement. We might never know for sure…