I purchased NMS online from Amazon ( ver 2.0) . Downloaded from Norton.com and received pop out window telling me to upgrade to latest version ( from google play store). I followed it and received and error message. Then I looked in here and found this solution: https://community.norton.com/forums/error-while-upgrading-nms-250420
I followed every single step and still am unable to upgrade so I have given up . Support on live chat advised me to get latest version, so did I! purchased AVG instead!