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

The March 17, 2026 Sims 4 update was a big one. It added the new in-game Marketplace on PC and Mac, retuned Sim autonomy, and shipped more than 60 bug fixes and quality-of-life improvements. (You can read EA's official patch notes here.) As with every major patch, some mods and CC stopped working afterward.

Here's what changed, what it tends to break, and how to fix it fast. For a deeper walkthrough of mod troubleshooting in general, see our complete Sims 4 mod troubleshooting guide. For the current patch, see the latest Sims 4 patch page; the August 2026 write-up covers the patch after this one.

What the Update Changed

• The Sims 4 Marketplace arrived on PC and Mac, with a new way to browse and manage downloadable content. Pack Select moved out of Game Options into My Collection inside the Marketplace.
• Autonomy was retuned. Sims are now less likely to flirt with strangers and generally prefer interacting with Sims they already know. Autonomous phone use got a six Sim-hour cooldown, and autonomous computer use got roughly a half-day cooldown.
• New preferences were added to the base game: Likes Phones, Dislikes Phones, Likes Computers, and Dislikes Computers — so you can control whether Sims reach for these objects on their own.
• 60+ bug fixes across gameplay, many addressing top community-reported issues.

What Tends to Break

Autonomy Mods (Highest Risk)

"No Autonomous [Action]" mods and autonomy overhauls (Meaningful Stories, Slice of Life, and similar) are the most likely to conflict with the new cooldown and preference systems. If your Sims start behaving oddly, look here first.

Script Mods

Any script mod (.ts4script) that hooks into the autonomy, preference, or relationship systems may need updating, because the game's Python modules in simulation.zip changed. Script mods are always the highest-risk category after a patch.

Relationship and Socialization Mods

Because the patch adjusted how Sims choose who to socialize with, mods that modify relationship or social behavior may produce unexpected results until their creators update them.

Pure CC (Lower Risk)

Most custom content (hair, clothing, furniture) keeps working. Patches occasionally re-tag catalog items, but that mostly affects EA content rather than 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

Large Mods folders can require many testing rounds.

Option 2: Scan Instead of Guess

Sims 4 Mod Fixer scans your whole Mods folder and checks every .package and .ts4script file against the game version you actually have installed. It flags likely broken script imports, outdated tuning overrides, duplicates, and conflicts, and shows the evidence behind each finding so you can decide what to set aside. A flag means "likely needs an update from its creator", not a verdict.

When a scan cannot prove the cause, its guided 50/50 tool tracks the rounds for you: it moves half of the remaining suspects aside, you launch the game and report what happened, and it narrows the list until one mod is left. You still launch the game each round, but you never rename folders or lose your place.

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 deaderpool-mccc.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 are worth checking 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 or socialization behavior
• Any mod that modifies game preferences or traits

Check each mod creator's Patreon, website, or ModTheSims page for updates. Update timing varies by creator.