Background lost after WP Update?

Hallo, since today i recognized, that the background of our theme is lost! The only changes i made yesterday, was updating WP to 4.7 and updated some Plugins too. But: I'm not able to update the Page Builder by SiteOrigin Plugin. There's an error that the download wasn't found. The reason for the problem? Our site should look like this: http://www.mzhd.de/events/kategorie/fortbildung/ (site is stored in cache, so the background is still the right one) But instead on the main page it's missing since today! -> http://www.mzhd.de Could someone help please? Thanks Greets Peter