For this error, first of all, please make sure that you are typing each and every letter correctly. If it's still giving you the same error, please follow the workaround below:

1. Press Windows key + X

2. Click Command Prompt (admin)

3. Enter the following command: wmic path SoftwareLicensingService get OA3xOriginalProductKey

4. Hit Enter

5. Copy the product key then enter it

6. Click Start > Settings > Update & security > Activation > Change the product key then enter the new product key we sent you > click Next to Activate

NOTE: If that didn't help, please feel free to open a new support ticket and include the details below so we can assist you better:

1. Order / Transaction ID

2. PayPal email address and/or Delivery email address (if different from PayPal email address)

3. Type manually the product key (code or pre-loaded account details)

4. Screenshot of the pop-up/error message

5. Additional information (if any)