DuckDuckGo Was Down?

Whenever I attempt to search anything, I get the following message...

Oops, there was an error. Please try again.

...Aaaannd it’s back up.

DDG tweeted about the outage here: https://twitter.com/DuckDuckGo/status/1284408766822113280?s=...

I am getting

        502 Bad Gateway
        ---------------
              nginx

what does it mean?