The "Server Error" pop-up showed up today for me, but I've been having issues with the Gallery for several days now. Yesterday it completely failed to load anything, but that's another matter.
Or is it?
Because after trying all I could to save one of my builds in my Library (repairing the game, removing mods, swapping folders, trying to save whilst in BB with occupants, without occupants, in live mode, with big lots, small lots, empty lots, you name it...), ONE copy of said build ended in the Library about 6h after the tests. My game at the time of the magic appearance was fully modded, mind me, I've put everything back.
And then I remembered, a couple of days ago I tried to download a horse from the Gallery, and it didn't let me. But what do you know? Hours later that horse was in my Library. Take all this as you must, I don't know if somebody else is experiencing these paranormal activities with the Gallery, most certainly I have no idea what's going on, except harbouring the strong suspicion that this is not an issue on the players' end.
I really hope they'll treat this as a priority. I don't mind playing offline, but atm BB is seriously crippled if not straight down knocked out because of this issue, and that means 1/3 of this game going to the dogs.