Ideas
I just installed the latest update, 2.11, I created a new game with a random generated sim, I built a test house and tried to upload it to my library, I still get the error message of which I attach the picture here, however after some seconds the uploading window behind the message closed, leaving only the message window, at that point I closed the message notification and checked on my library and it had uploaded the lot; afterwards, I tested it again with the same lot, this time it uploaded normally, no error message, however, since this is the sims4 I tried it yet a 3rd time and it showed again the error message but uploaded it to the library. In conclusion, it's a little better but not totally fine, they have to keep working on solving the issue completely.