Sul Sul, Simmers!

Over the past few months we’ve been sharing our progress with you as we work our way through concerns about save file issues, disappearing Lots, white screens, and loading problems. We know how frustrating it is when a beloved save doesn’t behave the way it should, and we want to keep you in the loop about the work happening behind the scenes to protect your hard-earned progress, stories, and creations.

Our team has been deep in the trenches testing, reproducing, analyzing, and building new tools, to understand the many factors that can contribute to save corruption. While there’s no single bug to fix that fixes them all, we’ve made meaningful progress across several key areas, thanks in large part to the saves and reports you’ve shared with us.

Here’s a recap of what’s been happening, where we are right now, and what our early 2026 plans look like.

Investigation, Fixes, and New Tools

At the start of this quarter, we kicked off a large-scale review of community-reported issues. We’ve been tracking everything from Lots disappearing in heavily populated Residential Rental worlds to white screens, endless loading loops, and cases where the game loads but saves show missing neighbors, objects, or builds. These issues vary widely with some only occurring on certain platforms, others only under very specific conditions, but we’ve been treating each one with care and urgency.

To support this work, we created a new Python-based tool that helps us analyze the structure and contents of affected save files much more efficiently. This tool has already helped us spot patterns in file size, mods, Lot complexity, and version history – giving our engineers more concrete leads to investigate. We’ve also built an expanding database of player-submitted saves, which helps us compare cases and identify common traits more quickly. 

What We’ve Fixed So Far

We’ve shipped several meaningful steps forward this quarter:

Infinite Loading Fix Released

• We identified an issue that caused infinite loading when converting Penthouses or Dorms into Residential Rentals, something that arose with Adventure Awaits. A fix was released in the November 4 Base Game update. 

Several Error Codes Solved in Player-Submitted Saves

• We’ve resolved the underlying causes of Error 109:4fe45107, 109:d7e16575, and 123:b378c837 in the saves where they originally occurred. These fixes were released in the December 2nd Base Game update, and if you see these errors again we want your saves so we can track down additional causes.

What We’re Investigating Right Now

Protobuf Overflow – A Leading Theory for Missing Lots

We’ve found compelling evidence that some cases of missing Lots or disappearing houses may be caused by what we call a Protobuf Overflow – a situation where Lot or save data grows so large it hits its storage limit. Our early testing suggests that the Memory Boost feature reduces this risk on some hardware configurations, and in certain cases, even makes missing Lots reappear when loading a broken save. This is an active area of testing and one where your data can heavily accelerate our progress.

Error 801 and Scratch File Behavior

Error 801 remains a top priority. Current findings suggest that multiple game processes may compete during load, causing inconsistent results. We’re also taking preventative steps by relocating scratch files from the Documents folder to AppData in an upcoming update to avoid conflicts with cloud backup services. 

Complex, Cheated, or Modded Lots

We’re testing how extreme builds like heavily decorated Lots, MoveObjects placements, or builds using cheats behave when placed into saves that don’t have those cheats active. Some of these cases can create unexpected complexity that the game struggles to resolve, especially when mods or custom Lot traits were involved.

Data Carrying Between Saves

In rare cases, data from one save can carry into a second newly created save in the same session. This behavior started in Lovestruck, and while it doesn’t explain older corruption reports, it does give us valuable insight into how systems interact internally.

Your Reports Continue to Drive This Work

Across this quarter, your reports, votes, comments, and shared save files have been essential to every discovery we’ve made. Many investigations like scratch file questions or Lot data inconsistencies began with specific saves you sent us. And when we say we’re still collecting saves, we truly mean it: every single one helps. 

To help us push further into the Protobuf and missing Lot investigations, we’ve put together a Missing Lot Data Survey. If you’ve experienced disappearing Lots, odd load behavior, or interactions between Memory Boost and missing data, this survey will help us gather the targeted information we need.

What You Can Expect in Early 2026

In early 2026 you can expect to see fixes for flea market items disappearing and reappearing, more fixes around photos turning black, our previously announced moving of scratch files, and more. For the scratch files, we will be staggering the roll out behind the scenes so that we can closely monitor for any issues before a full roll out to all players. You can also expect more updates from the team on our save file investigations, including testing around our investigations into mod data being shared via the Gallery. 

Thanks for sticking with us, for sharing your saves, and for helping us make The Sims 4 safer and more stable for everyone. Your willingness to share details, files, and feedback directly impacts the work we’re doing, and it accelerates our progress toward long-term fixes.

We’ll see you back here in January with more updates.

Dag dag!