Downloadable versions of Windows 10 version 1511, the November 2015 update, appear to have been removed after their release earlier this month.

Initially, Microsoft let people download full copies of the installer using the Media Creation Tool (MCT). Media produced with the MCT can be used to perform both upgrades and clean installations, and it's especially convenient when updating multiple systems, as it ensures that only a single download is required. But the version 1511 MCT has been removed, and replaced with the original July version. Systems can still be upgraded to the November update, but direct installation is no longer possible. Instead, the original RTM version must be installed, and the upgrade to 1511 performed through Windows Update.

This is both inconvenient and mysterious. The ability to install 1511 on clean systems is obviously quicker than going via the RTM version. It means one large download instead of two. Upgrading multiple systems with the MCT is also obviously preferable. It's mysterious because it's not really clear why the 1511 installer has been pulled. Microsoft's official comment explains nothing:

The November update was originally available via the MCT (Media Creation Tool), but the company decided that future installs should be through Windows Update. People can still download Windows 10 [Build 10240] using the MCT tool if they wish. The November update will be delivered via Windows Update. Microsoft has not pulled the Windows 10 November 10 update. The company is rolling out the November update over time – if you don’t see it in Windows Update, you will see it soon.

Problems with 1511 have been reported, and some of these may point at the reason for withdrawing the ISO images. The initial release was awkward for people who wanted to use their Windows 7 and 8 license keys to install Windows 10. It didn't allow clean installations, instead only supporting upgrade installs. The November Update was supposed to allow Windows 7 and 8 product keys to be used even for clean installations. But people found problems; for example, the install process defaulting to Windows 10 Home and not even offering the option to use a Pro or Pro-equivalent Windows 7 or 8 key.

There are also reports that clean installations of build 1511 aren't working properly with BitLocker. Upgrades seem to be fine.

Even when the operating system is installed, it's not bug-free. Your writer's experience is that 1511 is better than the July RTM release, but others are reporting all manner of bugs, such as machines that instantly wake after sleeping, excessive processor usage by the Mail app, the lock screen failing to hide the full desktop, and more besides. Given that Microsoft is still pushing 1511 out through Windows Update, none of these issues would appear to be fatal, showstopper issues, but clearly this release is not without its problems.

Brad Sams at Petri speculates that the bugginess is a result of Microsoft's new development approach. The way Windows is developed has changed radically as a result of two things: laying off large numbers of dedicated software testers, and shipping regularly both to members of the Insider program using pre-releases, and to mainstream users with monthly updates and twice-yearly larger upgrades (of which the November release was the first).

This has moved the testing burden to developers and to Insiders, and Sams reports that this switch has proven difficult. There used to be a roughly one-to-one ratio of testers to developers, with developers left relatively unhindered by the need to test. Now they need to spend their own time on testing, while all the while having to produce software that's good enough to ship on shorter deadlines.

These changes are arguably necessary in the longer term, to give Microsoft the flexibility and responsiveness it needs, but the current state of Windows is vexing, to say the least. The software that ships needs to be reliably more reliable if Microsoft is to successfully persuade enterprises to make the switch. Right now, it's creating reasons for them to stick with Windows 7 or 8, or Windows 10 Long Term Servicing Branch. The latter avoids some of the bugs, by changing less quickly, but also avoids many of Windows 10's new features, too.

Listing image by Guilherme Tavares