Apple released iOS 9.0.1 on Wednesday, only a week after rolling out iOS 9.0. The update fixes several issues such as Setup Assistant failing to complete, and alarms failing to play.
Apple fixes a handful of bugs with iOS 9.0.1 update
The iOS 9.0.1 update also fixed an issue where timers failed to play, corrected a problem that caused paused video to appear distorted in Safari and Photos, and fixed a problem where custom APN setups in profiles could cut off cellular data.
The update weighs in at 35 MB and is available by going to Settings > General > Software Update. You can also install the update by connect your iPhone, iPad, or iPod touch to iTunes via your USB sync cable.