Yes you can, rooted or not. You can download a custom Firmware for 'your' model..... and flash the new android version/firmware using an a pc software like 'Odin'. Note : - Since you're upgrading your version by flashing, you will lose all your data. So, try to backup. - and , as the second person answered. They rarely have consequences if not done properly. So, google more on how to upgrade using Odin. 1. Download Odin for pc 2. Download a firmware for your phone model specifically. 3. It's easy after that, just follow the rest of the steps from any credible website.