Re: A serious error has occured while loading [world]

@noobieheng  Please try the Mods Framework found here:

http://modthesims.info/wiki.php?title=Game_Help:Installing_Sims_3_Package_Files/Setup_and_Files

Don't add any of your own mods yet; just see whether the two sample mods work.  If they do, you can add one freshly-downloaded mod and test that too, then more if that one also works.  Delete scriptCache.package each time you add (or remove) a mod.

If you get the same error with only the Mods Framework's sample mods in place, let me know what game version the launcher shows in the lower-left corner.  Please also let me know what kind of install this is: EA App, disc, Steam, or something else.