Error code 800 (on Xbox)

Unfortunately thats not much we can do on this situation :(

I already lost 3 full save files to the Load error aka save corruption and theres no way back. 
And it's always like this: you create your entire save file and starts playing with a family in another neighborhood/world to then realize after a week or so that Willow Creek is already gone - some times Newcrest or even Oasis Springs too. 

Some people are trying to fix their own save game by using the Sims 4 Studio and resetting the corrupted lots but the Load Error comes back eventually 😔

I’ve already been into Sims 4 Studio to reset one Willow Creek lot but im not sure how long that’ll last…this bug is horrible and I really hope EA can fix it before they try to push out more packs because I unfortunately will not be buying if they keep this up

You have to do exactly this. I did this earlier this year. I'd even stray away from bringing in old lots, and just rebuild them. Save your families and sims into gallery and rebuild the game. I'm not a tech person so excuse my explaining but I found out that it'll just keep happening eventually if you don't completely wipe the game from your computer. Literally uninstall it, and reinstall it again and manually place back in mods (if you use them) and start a new save file with the sims you uploaded to the gallery.. then cheat their relationships etc. It took me a few weeks because I lost a 6 year old legacy save file.. Was devastated. 

I still am staying away from creating rental lots which is a **bleep** shame because that was the one feature I was actually excited for in the sims. My games been okay so far, but I backup my save files onto external hard drives like once every two weeks or so because I'm a bit traumatized to say the least. 

I really hope they fix this.