Why doesn't my valid product key work after uninstalling Ubuntu?

The issue you're experiencing with your product key not working after uninstalling Ubuntu could be due to several reasons:

1. Product Key Not Tied to BIOS: If your product key is not tied to your BIOS, it may not be recognized during the Windows installation process. Many prebuilt systems come with OEM activation keys that are embedded in the firmware, which allows Windows to activate automatically. If your key was not stored in the BIOS, you may need to enter it manually during installation.
2. Windows Edition Mismatch: Ensure that the product key you are using corresponds to the same edition of Windows that was originally installed (e.g., Home, Pro). If you attempt to install a different edition than what the key is for, it will not activate.
3. Installation Media: If you are using installation media that does not match the version of Windows that your product key is for, this could also lead to activation issues. Make sure that the Windows version you are installing is compatible with your product key.
4. Previous Installation: Sometimes, if the previous installation of Windows was not properly deactivated or if there were remnants of the Linux installation that interfered with the Windows setup, it could cause activation issues.

To resolve this, you might want to try the following:

• Verify that you are using the correct product key for the edition of Windows you are trying to install.
• If possible, check if there are any OEM-specific activation tools provided by the manufacturer of your desktop.
• Consider contacting Microsoft support for assistance with activation issues if the problem persists.

References:

• Windows installation fails with error: The product key entered does not match any of the Windows images available for installation. Enter a different product key
• Work with product keys and activation
• Windows Setup Edition Configuration and Product ID Files (EI.cfg and PID.txt)
• Troubleshoot issues in ESU

Hello, Shea.

Check if there really is a key in the BIOS or not. To do this, run the Command Prompt as an Administrator and run the command

wmic path softwarelicensingservice get OA3xOriginalProductKey

If the result is a 25-digit key, it means that the license was installed by the PC manufacturer and it is possible that you made a mistake with the Windows edition (Home, Home for old language, Professional) when reinstalling the OS.

If there is no key in the BIOS, and the OS is pre-installed (OEM) by a small PC assembler/seller, then in this case a COA (certificate of authenticity) must be glued to the case of the system unit, on which information about the OS edition and the product key must be pasted. Check if the COA revision matches the one actually installed.

If an offline version of Windows (BOX or ESD) was installed on the PC, then the seller, when transferring the PC with the OS license, was obliged to transfer to you either the complete BOX set (including the product key card), or documents confirming the purchase of the electronic version (ESD), including a receipt with a printed product key.

If none of the above is available, then unfortunately, there is a high probability that an unlicensed (pirated) OS was installed on the PC, activated illegally. In this case, the problem can only be solved by purchasing a license for the standalone version of Windows and installing it cleanly with the activation key from the license purchase package.