Update 24-Nov-2015: Microsoft has restored the version 1511 media creation tool and explained the reason for its temporary disappearance. For details, see "Microsoft reverses course, restores downloads of Windows 10 November Update."

When Microsoft released Windows 10 version 1511 earlier this month, the company also updated the installer files it delivers via a free, downloadable media creation tool (MCT).

Company executives even recommended the tool to Windows 10 users who were too impatient to wait for the upgrade to arrive via Windows Update.

That upgrade option worked as advertised for more than a week. This weekend, however, the new files have been pulled and the media creation tool available for download from that page instead installs the July 2015 (build 10240) release.

Update: A Microsoft spokesperson says the change is intentional:

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.

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?

For now, at least, the 10586 media creation tool is still available from a hidden link on Microsoft's servers. See the note at the end of this article for details.

These are the file properties of a copy of MediaCreationTool.exe I downloaded early on November 12:

Downloading the tool from the same page today results in a file with an earlier version number: 10.0.10240.16480.

The sudden change didn't come with any official explanation. The only documentation is a line added to the download page, warning, "These downloads cannot be used to update Windows 10 PCs to the November update (Version 1511)."

The ISO files for version 1511 are still available for MSDN subscribers.

My tests confirm that upgrading using this tool no longer delivers version 1511 but instead upgrades Windows 7 and 8.1 PCs to the original Windows 10 release.

Microsoft has also, again without notice, revised its Windows 10 installation notes. Via Twitter, Tero Alhonen provides these before and after links to the Windows 10 November update FAQ.

Here's the original text:

And here's how it reads today:

I've also heard unconfirmed reports that delivery of the November update via Windows Update has also stopped, and I've been unable to update several machines here in the past few days. A Microsoft spokesperson says this too is perfectly normal: "We are rolling out the November update over time - if you don't see it in Windows Update, you will see it soon."

See also: How to take control of Windows 10 updates and upgrades (even if you don't own a business) | Windows 10 Edge: How Microsoft is clamping down on browser ad injectors | Windows 10 telemetry: Time for a level playing field

One by-product of the sudden move is that the multi-edition installer, new in the November update, is no longer available. The current download links require the user to choose between x86 and x64 versions; the now-vanished replacement was a single executable.

Another by-product is that anyone upgrading from Windows 7 or Windows 8.1 to Windows 10 today has no choice but to accept a 3 GB upgrade to build 10240, followed a month later by an equally large second upgrade to version 1511.

And to add insult to those injuries, the sudden removal of the build 10586 ISO files means that the newly added capability to do a clean install using a Windows 7 or Windows 8.x product key is now unavailable to the general public unless they were fast enough to download and save an ISO file before the change.

Update: The version 10586 Media Creation Tool is still available from an unpublished link on Microsoft's download servers. Microsoft will probably remove it before long, but for now at least it works to upgrade systems running the original (build 10240) release of Windows 10 or to create a version 1511 ISO file.