You might see this error if you entered an invalid product key or a product key for a different version of Windows. Enter a valid product key that matches the version and edition of Windows 10 installed on your device. You may try these steps below:
1. Click on the Troubleshoot tool at the bottom of the error message.
2. Restart and/or update your computer, then enter the 25-digit activation key.
However, if the above solution does not work or you do not wish to do the solution above, please contact our Customer Support Team via Support Tickets on your EF Dashboard so we can check if you are eligible for a refund or replacement.
To assist you better, please include the details below
1. Order ID
2. Screenshot of the pop-up/error message
3. Additional information (if any)