Ideas
Patch notes state that the server error message is a legit message but was occurring too often. I'm not really sure when it occurs.
Do you just have it on that one lot ? Can you upload it to the library ?
crinrict , I created three lots yesterday and had the errors on each. Two were Residential Rental and one was Residential. There seemed to be no common circumstances for the error, for example, the first Residential Rental lot was densely decorated so I presumed that was the issue. I removed about 70% of the objects, reduced the number of units, moved the building to another lot, removed my limited mods (McCmd, etc.), deleted the lot from my library and resaved them, cleared the cache, restarted, and probably on the sixth attempt I think it finally loaded. The Residential lot was a small one, New Moon Shack/Moonwood. Again inexplicable server errors and in this case the game was started with cleared cache and no mods. It is on the gallery now as Old New Moon Shack (user id Wndblwz)