If you’ve ever encountered an error message like this in The Sims 4 when using mods? You might be wondering what it means and how to fix it. Let’s break it down step by step…

Why Does This Happen?

There are two main reasons why this error occurs

• Outdated Smart Core Script – The mod mentioned in the error message requires a newer version of the core library. The version detected on your computer is incompatible with the installed mod version. Simply delete all old versions of the script and install only the required one. If the message lists a version lower than the one you already have installed, this indicates that you have duplicate copies of the mod mentioned in the message. Update this mod and remove all duplicates!
• Duplicates or Conflicting Versions – You may have multiple versions of Smart Core Script installed or different versions of the same mod, with each requiring different versions of Smart Core Script. This leads to conflicts and can cause serious errors in the game — with different versions overwriting each other, resulting in critical issues and game crashes. One common symptom of this (although not always) is a message when launching the game, strangely asking you to install an older version of Smart Core Script than the one you already have installed. In this case, you need to remove all duplicate copies of both Smart Core Script itself and any mods that require Smart Core Script.

How to Fix It

Step 1: Update the Core Script

Check the website or platform where you downloaded the mod and look for the latest version of the required core mod. Install it and replace any older versions. Here are the two scripts I use in my mods:

• Smart Shared Core Script
• P.S.O. Shared Library

Which of the two scripts you exactly need is mentioned in the error message!

Step 2: Remove Duplicate Versions

Go to your Mods folder (Documents/Electronic Arts/The Sims 4/Mods) and make sure you don’t have multiple versions of the same core scripts or package mods. If you have a lot of mods, you should also check all subfolders! My mods and scripts always have a version number in their file name so you always know which versions you have.

Step 3: Enable Script Mods in the Game

Ensure that script mods are enabled in the game settings. You can read more about it here.

Step 4: Make a good support request

If none of this helped, post a good and detailed support request on my Discord. You can read more about it here. Don’t forget to be polite and be patient, because I’m neither a robot nor your employee. I’ll correct the error when I have time. However, most errors don’t need to be corrected because they are caused by you doing something wrong. I’m sorry for the bitter truth.