Simple four steps to help you solve the common activation problems of Win10

Most users will be automatically activated after upgrading to Windows 10, as long as you are using a genuine system or have entered a 25-digit product key. However, there are indeed unfortunate users who will encounter problems that the system cannot be activated normally. How can this be solved? If your computer was running genuine Windows 7 or 8.1, then the system should be automatically activated after upgrading to Windows 10.

Understanding Windows 10 Activation
The system will store what Microsoft calls "Digital License", which will register your system on Microsoft's product activation server to make it run Windows. 10 conditions.

Even if your system is not genuine, you can upgrade your system and purchase upgrades from the Windows Store. If you are asked to enter a product key when installing the system, click Skip.
But if you are using a mounting media such as a boxed disc or a digital download, you will need to enter the product key. Even if you buy a new machine with Windows 10 pre-installed, the product key will be included on the box or body. You need to take care of it, because Microsoft will ask you to re-enter it when you reinstall the system, even if you have activated the system before.
If you are a member of the Windows 10 Insider project, the product keys that were previously used to activate the Technology Preview are now unusable and they cannot even be used to activate older system versions. If you are joining the Insider preview project now, you will need to upgrade and activate the official version of Windows 10, then choose to get the Insider preview version from the Upgrade Settings menu.
Cleaning installation problems
If you choose to clean the installation during the upgrade, you may run into activation problems. So when performing a clean installation, you need a little trick: you can perform a restore factory-installation before installing Windows 10—— instead of directly formatting the computer —— then there will be no problems with activation. You can also upgrade to Windows 10 by standard steps and then use the Windows 10 installation tool to perform a clean installation after the system is successfully activated.
If you are upgrading from an ISO or multimedia installation media, you can choose to "Upgrade this PC" instead of "Install Now", which ensures that the installed version of Windows 10 matches the computer currently running. system version.

Starting with Windows Insider Build 10565, you can now activate Windows 10 directly with the Windows 7, 8, and 8.1 keys. To do this, select Settings > Upgrade & Security > Activate, then click Change Product Key. If you have performed a clean installation, you can enter it during the installation step.
Similarly, the version of Windows 10 you have installed needs to match the version of the system represented by the product key. For example, you can only use Windows 7 Premium/Fairball or Windows 8 Premium to activate Windows 10 Advanced. Some of the OEM keys for Windows 8 and 8.1 computers are stored in firmware, and since 10565, Windows 10 can also be used for activation.
Processing Activation Issues
After upgrading to Windows 10, you should first go to Check Settings > Upgrade & Security > Activation to see if the system is successfully activated. If you can't click the activation button, you can wait a few days and most systems will be activated automatically in the background.
If you still can't activate, you can try a different network connection. It should be noted that if you are networked through a proxy server using basic authentication, then Windows cannot be activated.
If the system displays 0XC004E003, 0x8007000D, 0x8007232b or 0x8007007B, this error code indicates that Microsoft's activation server load is too high and the installer cannot verify your installation ID through them.
Automatic phone activation
If you don't want to wait, you can try the automatic phone activation method. The specific method is to click the Windows key + R, enter "SLUI.EXE 4", select your country, and then you will see a free number and installation ID. You need to dial this number, enter your installation ID, and click the “Next” button. Subsequently, Microsoft's automated system will read an installation key to you, you need to enter it into the SLUI dialog.

If you want to reset your product key and force an upgrade, you can enter the "SLMGR.VBS –REARM" command in the "Run" window, click OK and restart your computer, then enter as usual Product key. You will then need to enter “SLMGR.VBS –ATO” for forced activation.

If you are unable to enter the product key, you can use the “SLMGR.VBS -IPK XXXX-XXXX-XXXX-XXXX” command (replace X with the product key) and restart.
If you see the error code 0xC004F061, which means that you don't have a previous version of Windows to upgrade, you can install Windows 7 or 8 first, or use the corresponding product key to solve the problem.
Error code 0xC004C008 indicates that the product key you entered is already in use by another computer. If you are using a key that can activate multiple systems, this indicates that it has exceeded the activation limit.
The above is the most common problem encountered during the activation of win10, share it with everyone, I hope to help everyone's learning.