On Twitter’s earnings call yesterday, CEO Dick Costolo said its nearly flat user growth in the fourth quarter was partially the result of an iOS 8 bug. He didn’t explain it very well confusing analysts and journalists alike. On Friday, Twitter backtracked on that explanation. It tweeted, “To clarify from yesterday’s call: there was no bug or issue with iOS 8. It is an issue on Twitter’s side as users upgraded.” For a deeper explanation on what might have happened, read this.