PSA: YOU MUST UPGRADE YOUR EXISTING WINDOWS OS TO GET A VALID WINDOWS 10 KEY BEFORE DOING A CLEAN INSTALL
You don't get your free valid Windows 10 activation until you've done an upgrade of an existing Windows 7 or 8.1 installation.
You can check your activation status in Windows 10 by going to Control Panel->System applet. The activation status will be shown towards the bottom.
Afterwards if you wish to do a clean install via a bootable USB or DVD drive you can do it with the downloads provided from the following link : https://www.microsoft.com/en-us/software-download/windows10
If you're having problems getting the upgrade process started you can use the Media Creation tool linked above and have it create either a USB or ISO for you. Then from the USB drive or DVD/Mounted ISO run the setup.exe from the media's root folder. This method will still let you choose to keep your existing files/programs and will activate fine through the free upgrade offer. Make sure to choose the correct language, architecture (x86 or x64) and edition of Windows that applies to you. Note:
A product key is not needed if you're already activated via an upgraded installation.
Note If you upgraded to Windows 10 on this PC by taking advantage of the free upgrade offer and successfully activated Windows 10 on this PC in the past, you won't have a Windows 10 product key, and you can skip the product key page by selecting the Skip button. Your PC will activate online automatically so long as the same edition of Windows 10 was successfully activated on this PC by using the free Windows 10 upgrade offer.
If you wish to keep a record of your old Windows 7/8 key before the upgrade you can use a tool like Nirsoft's ProduKey (http://www.nirsoft.net/utils/product_cd_key_viewer.html
) or The Ultimate PID Checker (http://janek2012.eu/ultimate-pid-checke
). WITH THE FREE UPGRADE OFFER THERE IS NO NEED TO RECORD YOUR NEW WINDOWS 10 KEY. THE KEY YOU GET IS A GENERIC OEM KEY. YOUR WINDOWS ACTIVATION IS TIED TO YOUR HARDWARE NOT A PRODUCT KEY
Your free activation is tied to your hardware, you can change/upgrade your memory or hard disk without losing your activation. However, if you change out your motherboard you will lose your activation. If you're within the free year upgrade offer you can install your old operating system and go through the free upgrade activation process again. If you're beyond the free year activation period you can try calling Microsoft support and have them re-activate Windows 10. Microsoft has no official stance on what happens if you lose your activation through a hardware change so your mileage may vary.
An alternative to a clean install from a bootable media is to reset your current installation. This can by done by clicking the start menu and typing "Reset this PC". You can either remove everything and reinstall Windows for a factory reset, or refresh your PC without losing your files to only remove programs and settings. (http://windows.microsoft.com/en-US/windows-10/refresh-in-windows-10
I'm starting to see the same story over and over again of people skipping to the clean install procedure and are lost when Windows asks for a key. I think this should be a PSA to avoid future headaches should the powers that be make it so. Upgrade Tips https://www.reddit.com/Windows10/comments/3ew2z9/windows_781_to_10_upgrade_tips/
submitted by ThaBearJew
Upgrading to Windows 8 to 8.1
I have a SurfacePro, which I bought with Windows 8. I should be able to upgrade to 8.1, however, it is not appearing in the Windows Store.
I followed the troubleshooting on this
article. My PC has the KB 2871389 update. My version of Windows 8 is eligible, and I cleared the Windows Store Cache.
Microsoft won't let me download the ISO without an 8.1 product key, but to get one of those, I would have to buy a new copy of windows.
submitted by RewenX