This indicates a server timeout. Your local firewall or internet service provider is blocking Norton's security ports.
Double-check your spelling. If the key is correct, it means the key belongs to a different Norton product line (e.g., trying to use a Norton Antivirus Plus key inside a Norton 360 app). Final Thoughts norton 360 product key activation work
If you previously entered the product key on the web portal, it is permanently linked to that specific Norton account. Trying to enter that same key into a different account or an unlinked app will result in an error. This indicates a server timeout