As of today I cant accept a trade offer anymore, not for resources and not for referrals.

I can put up trade offers myself, but not accept an existing offer.

The game gives a popup with the tekst: Error, our field technicians are performing scheduled maintenance, etc. etc.
 

http://prntscr.com/dal9xt

Restarting the game did not work.

I have asked members in my combine if they have the same problem, they do.