Consistent "One or More Files Requiring Update in Use" Update Error
Yesterday I played my game just fine in the morning before work. It saved and closed with no issue. When I came back from work, the game suddenly wouldn't play. It gave me this message: "Unable to start due to missing game data. Please download The Sims 4 Legacy Edition from Origin." I searched the forums and found a thread saying the "resetting the game to factory settings without reinstalling" method helped. However, it made the issue way worse. Origin switched to giving me the error: "There was a problem while updating your game. One or more files that requires an update may be in use. If the issue persists please restart your computer and resume the update." I tried to repair the game, but that dragged me into a rabbit hole where the finalization of the repair would give an error, not let me cancel the repair, and wouldn't let me do anything else to the game other than restart the finalization of the repair. So, I gave up and uninstalled both the Sims 4 and Origin. I let my computer run the whole night to reinstall everything only to wake up to a bunch more "There was a problem while updating your game..." errors. They cancelled out all of the attempted installations. I thus tried clearing the Origin cache and running Origin as an administrator as proposed here to no success. I didn't try running the system in a clean boot as the linked page mentions trying to do that can result in your computer becoming unusable, which makes me nervous to attempt it.
So now I'm stuck here. Every time I try to install the base game, after hours of waiting I only get the same error above with little clue how to do a more clean reset of the files than an uninstallation because the game isn't even installed anymore. I have Avast, and all the Origin/EA/Sims folders have long been whitelisted. I doublechecked, and they still are.
Is doing a clean boot installation my only hope, because I really have no clue what else to do.
@iButterfree What antivirus program do you use? It may be preventing Origin from properly installing Sims 4, either because Origin.exe is blocked or because TS4_x64.exe gets flagged. The initial error you saw is often related to the game .exe being blocked or even deleted.
You can try setting exceptions for both .exe files in your antivirus, but that's often not enough—some programs have additional features that need to be disabled. If you just want to cut through the various options, you can disable your antivirus entirely while downloading, then mess with its settings after the fact.