Discovery engine, StumbleUpon is down at the moment

Discovery engine, StumbleUpon is down at the moment. When I log on to the website, I was greeted with this message ''looks like there is a problem. But don't worry, we are working quick like a bony to fix it, and everything will be back to normal soon'' according to the message.
A few days ago, I learnt that LinkedIn encountered same problem, but was immediately brought back to normal.