[Tomgs]

The planets rioting have a lot to do with your happiness type you picked at the beginning of the game. Parking the ships over the planet works best for peaceful types colonizing and building facilities on the planet help them too. So does trade and higher treaties. If you are at War that will hurt the happiness. If you picked neutral anything you do will cause unhappiness doing nothing for a while is the best thing for them don't meet new empires don't make treaties or war. Bloodthirsty is my favorite declare a war, build ships on the planet (before they riot this makes them very happy), win some space battles nearby, but don't colonize or make any trade or better treaties. All the happiness facilities help but no method is fast they all take time to work so always plan ahead and build those facilities fast.