After a processor change Windows demands activation and won't recognise original key.

When you change hardware components like a processor, Windows may require reactivation because it detects significant changes in the system configuration. If Windows is not recognizing your original key and indicates that it is invalid or already in use, it could be due to the key being tied to the original hardware configuration.

Here are some steps you can take to resolve the activation issue:

1. Use the Activation Troubleshooter: Since you've already tried this, ensure that you select the option for hardware changes. If this does not work, proceed to the next steps.
2. Contact Microsoft Support: If the troubleshooter fails to resolve the issue, you can reach out to Microsoft Licensing Activation Centers for assistance. They can help you verify your original key and may provide a solution without requiring you to purchase a new key.
3. Check for a Digital License: If your Windows version is linked to a Microsoft account, you might be able to reactivate it by signing in with that account.
4. Re-enter the Product Key: Sometimes, simply re-entering the product key can resolve the issue. Make sure to enter it correctly without any typos.

If these steps do not resolve the issue, you may need to consider purchasing a new key, but contacting support first is advisable to explore all options.

Hi,

how did you purchase this license and what this license was? Could it be you have Windows 7 or Windows 8 license? Such licenses cannot be used for Windows 11 (re)activation.