What are Last Exception Files? 'Last Exception' and 'Last UI Exception' files are created to let you know that there is something wrong with your game. This can be anything from a core game error to a broken mod or custom content item that you have installed. Last Exception files and Last UI Exception files are .txt format files that are generated in you Documents/Electronic Arts/The Sims 4 folder. You can open these up in notepad to take a look and see what is causing you errors. Keep in mind that any mod that changes the UI or are script mods will most likely need to be updated after a new patch. You can check with the creator of the mods you are using to see if there is a new update. Occasionally custom content breaks after major changes made by EA (this is rare, but does happen) and that can also cause you to have game issues and give you Last Exception errors.