Everything you know about upgrading to Windows 10 v 1511 -- the Threshold 2/build 10586/Fall Update -- is pretty much wrong. As of very early Monday morning, the only way you can get to Win10 v 1511 is by installing the old July 29 RTM Win10 build 10240, then waiting for Windows Update to offer to upgrade you to version 1511.
In particular, this is what happens if you upgrade from Win 7 or 8.1 to Win10. If you use the Windows 10 Media Creation Tool, either telling it to Upgrade now or to create upgrade media, you'll get build 10240 and not build 10586.
What I told you about upgrading to build 10586 last week, and two weeks ago, is all wrong. Everything you read on the Microsoft site, including the Answers forum, is wrong -- although the Media Creation Tool page has been changed to reflect the current state of affairs. Everything you read everywhere online is wrong. Your Windows 10 guru buddy is wrong. Microsoft changed everything, apparently late Friday night, without any advance warning or explanation.
Another way to look at it: If you want to upgrade from Win7 or 8.1 to the latest Win10, you'll have to sit through two 3GB to 4GB downloads.
I first heard about the change when Ed Bott ran a damning piece in ZDnet on Saturday afternoon. He quotes a Microsoft spokesperson as saying:
The November update was originally available via the MCT tool, but we've decided that future installs should be through Windows Update. People can still download Windows 10 using the MCT tool if they wish. The November update will be delivered via Windows Update.
Bott's response is spot-on:
Frankly, that explanation is pretty hard to accept. Nine days after the company encouraged people to use this tool for upgrades, it's pulled on a weekend, with no explanation? And if the decision is truly that "future installs should be through Windows Update," why interrupt this update after untold numbers, probably millions, have already downloaded the setup files?
Many people, including Bott, have remarked that the Windows Update version of v 1511 isn't showing up on their 10240 RTM machines. Microsoft says it's "rolling out the November update over time" -- which means Microsoft can completely stop rolling out the updates if it desires, and nobody would be any the wiser.
Why did Microsoft suddenly change its mind and make a hugely unpopular decision on Friday night before Thanksgiving? Theories abound, but the most-baked one I've seen comes from Microsoft MVP Greg Carmack. Writing on the Microsoft Answers Forum, Greg posits:
This may have to do with a glitch also reported here on Monday that on Clean Installs that media was reading embedded Windows 8 keys to only activate the embedded version, even on PCs that also had a Digital Entitlement to Pro version. Since the version menu was then hidden, there was no way to install Professional without a workaround that was posted later in the week by MS in the thread here: How to upgrade 1511 from Home to Pro? - Microsoft Community.
Since there is no response from the Windows 10 Team yet, we assume they are scrambling to resolve issues with Entitlement activation which, unfortunately, was the only feature not able to be tested (or Stress Tested, as August proved) by the 5 million Insider previewers, who used keys.
That seems to me to be the most likely proximate cause: The 1511 direct installer was erroneously installing Win10 Home on machines that qualify for Win10 Pro. Instead of fixing the problem, the Windows team brought down the whole shooting match ... on a Friday night ... with no warning or explanation.
If you have a copy of the v 1511 ISO running around -- you might've created it with the Media Creation Tool prior to last weekend, or you can still download it from MSDN -- you can still upgrade straight to 1511. But if you don't have one in your back pocket, you get to upgrade twice.
Why do I get the feeling that Microsoft is making this up as it goes along?