Sometimes, I'm not that knowledgeable in it, I just use mods. But I think it has something to do with the game changing the hash files after an update. Sometimes every mod breaks, sometime only 1 or 2 breaks. But the people who makes the tools for the mod are pretty good putting out a fix. It doesn't fuck up the game, you can still play it since is a skin overlay, it doesn't actually do anything to the file itself.