More Windows 10 Answers: How Activation Will Work on an Upgrade

While we still don’t know whether Microsoft will provide Windows 10 ISOs—hint: they almost have to—a leaked version of the Windows 10 release notes finally puts some other important questions around product activation to bed.

And to be clear, this is good news.

Also good: I’ve seen this exact behavior (described below) already. I wrote yesterday in Windows 10: A Tale of Two Mini-Tablets that, regardless of how I installed Windows 10—upgrading from previous OSes through Windows Update, installing via USB-based Setup using an older build of the OS—the system would eventually upgrade to the final shipping version of the OS … and would be fully activated. This, as it turns out, is by design.

A newly-leaked portion of the Windows 10 release notes (courtesy of WZOR on Twitter) explains what’s happening with regards to activating upgrades or clean installs of Windows 10 on existing hardware.

“The product key is not needed for testing purposes,” the notes read. “Partners … can perform boot-from-media clean installations of Windows 10 without being required to enter the product key during setup. Windows will not activate, but it should not impact functionality for your testing purposes. If you run Windows 10 setup for an activated down-level OS, you will not be prompted for a key as long as the edition of the down-level OS matches the Windows 10 edition that you are upgrading to. If you try a cross-edition upgrade of Windows 10 (for example, from an activated Windows 10 Home edition on build 10163 to 10240 Windows 10 Pro, then you will be prompted for a product key.”

There is lots of information there. And while this applies to “partners,” I can tell from my own experiences upgrading dozens of Windows PCs, tablets, and other devices up through Windows 10 build 10240 that this information pertains to all of us. So let’s step through what this explains.

ISOs are a virtual certainty. Microsoft made Windows 10 ISOs available during the preview period. Microsoft today makes ISOs available to anyone publicly. Microsoft is making ISOs (which are used to create those “boot-from-media clean installations of Windows 10” mentioned above) available to partners. We will all be getting ISOs. I am sure of this without literally knowing it to be true. (How’s that for wiggle room?)

You can clean install Windows 10. This means you can clean install Windows 10 on any PC. Whether it will activate without a product will depend on the factors mentioned below.

A clean install or upgrade of Windows 10 will automatically activate on an existing PC if you follow the rules. That is, it must have come with Windows 7 or Windows 8. And the version of Windows 10 you install must match the version of the previous OS. If you had Windows 7 Home Basic, for example, you must use Windows 10 Home. If you do, it will work. If you don’t, you will be prompted to activate and you will need a Windows 10 Pro product key.

That latter point is absolutely borne out by my own testing.

Obviously there are more questions. Will Insiders and others who reserved Windows 10 actually get or even need product keys? When will ISO become available (July 29/later)? And so on. But little by little, the information is dripping out.