I occasionally encounter this error while PMing. It just means that traffic is heavy for this site on its internet gateway server - I've seen recently that there have been and still are periodic "spikes" of users viewing the various subsections of the General area. If you wait one to two minutes after encountering the error and then refresh your browser, it usually clears up by itself. If it still is not cleared up then wait for a longer period (e.g. - Three to four minutes) and then try refreshing your browser again. For more information about "502 Bad Gateway Error", see "What causes a 502 Bad Gateway error?" in the following article ->
here. Because it (Server overload) is sporadic, nothing practical AFAIK can be done on the server side to remedy it (And as a user on the client side, all you can do is wait and refresh). I hope that this helps!
o_o
BTW - This message actually belongs in the "
Questions & Answers" section.