How to Fix Broken Sims 4 Mods After the March 2026 Patch

Updated: March 17, 2026

The March 17, 2026 Sims 4 update is one of the biggest patches in recent memory. It introduces the Marketplace, overhauls the autonomy system, adds new preferences, renames relationships, and includes 50+ bug fixes. If you use mods or CC, some of them will break.

Here's what's affected and how to fix it fast.

What Broke and Why

Autonomy Mods (Highest Risk)

The patch adds cooldown timers to dozens of autonomous interactions — computer use, swimming, instruments, dancing, exercise, and more. If you have any "No Autonomous [Action]" mods or autonomy overhauls, they will likely conflict with the new cooldown system.

Script Mods

Any script mod (.ts4script) that hooks into the autonomy, preference, or relationship systems may need updating. The game's Python modules in simulation.zip have changed.

Relationship Mods

The "Super Sibling" relationship type has been renamed to "Childhood Besties" and "Childhood Frenemy." Mods referencing the old name will break.

Pure CC (Lower Risk)

Most custom content (hair, clothing, furniture) should still work. Dozens of items were re-tagged for catalog categories, but this mostly affects EA content, not CC.

How to Find the Broken Mods

Option 1: The Manual Way (50/50 Method)

1. Remove half your mods from the folder
2. Launch the game and see if it works
3. If it works, the problem is in the half you removed. Put that half back and remove the other half.
4. Keep splitting in half until you find the broken mod
5. Repeat for every broken mod

With 500+ mods, this takes 3-5 hours. With 5,000+ mods, it can take an entire day.

Option 2: The Fast Way

Sims 4 Mod Fix scans your entire mods folder in minutes. It checks every .package and .ts4script file against the current game version, finds broken script imports, outdated tuning overrides, and conflicts — then tells you exactly which mods are the problem.

It can also run the 50/50 method automatically. Instead of manually moving folders for hours, it does the whole process in the background and tells you which mod crashed your game.

Quick Fixes You Can Do Right Now

1. Re-enable mods after the patch. Every Sims 4 patch disables script mods automatically. Go to Game Options → Other → check "Enable Custom Content and Mods" and "Script Mods Allowed." Restart the game.
2. Delete cache files. Go to Documents/Electronic Arts/The Sims 4 and delete: localthumbcache.package, and everything inside the "cache" folder. The game rebuilds these on next launch.
3. Update MCCC first. If you use MC Command Center, update it before anything else. It's the most common script mod and frequently needs updating after patches. Get it from deaderpoolmc.com.
4. Check Scarlet's Realm. Their mod compatibility list is updated after every patch with which mods are broken and which are confirmed working.
5. Remove mods you don't recognize. If you've been downloading CC for years, you probably have mods you forgot about. Old, unmaintained mods are the most likely to break.

What to Update

These types of mods should be checked for updates after the March 17 patch:

• MC Command Center (MCCC)
• UI Cheats Extension
• Better Exceptions
• Wicked Whims / Wonderful Whims
• Any "No Autonomous [Action]" mods
• Autonomy overhaul mods (Meaningful Stories, Slice of Life, etc.)
• Any mod that changes relationship behavior
• Any mod that modifies game preferences or traits

Check each mod creator's Patreon, website, or ModTheSims page for updates. Most popular mod creators release patches within 24-48 hours of a game update.