Error when syncing Creative Cloud (Mac)

I'm adding myself to the large group of Adobe users experiencing problems with Creative Cloud and unable to find help or reach support...

My problem is that CC starts syncing, reaches 93 %, and then quits with the unhelpful error message "Unable to sync libraries". I've tried every trick I could find in the forums but nothing helps. I can't even find a logfile to look at!

Can someone give me some hints on where I should look and what I should do to remedy this? I'd be very grateful!