Exclusive: Sims 4 Unable To Start There Was An Error Processing The Startup Configuration Script

Warning: Only do this if you are comfortable editing the Registry. Back up your registry first.

This error sometimes stems from a stale Windows Mutex (a mutual exclusion object) that wasn't released on a crash.

If the configuration script itself is missing or corrupted from a bad update, you need to force the launcher to re-download it.

For EA App (Modern):

For Steam:

For Origin (Legacy):

Microsoft OneDrive is a frequent culprit. If it is syncing your Documents folder, it locks files milliseconds before Sims 4 tries to access them.

This error indicates that the game cannot read or execute its internal startup script (likely a Lua or Python configuration file) due to a corrupted, missing, or incorrectly modified file. It is rarely caused by hardware issues and is almost always software-related—often due to mods, broken game files, or permission problems.