If you've upgraded your iPhone or iPad to iOS 9 and it is stuck on the 'Slide to Upgrade' screen, this is the fix you're looking for.
The fix, which is detailed on the company's knowledgebase website, is as follows:
- Connect the iOS device to a computer running iTunes (Thought we were in a post-PC world? Think again.).
- Select your device from within iTunes. If you don't see it listed in iTunes then you'll need to force a restart by pressing and holding both the Sleep/Wake and Home button for at least 10 seconds, until the Apple logo appears.
- If you made an iTunes backup of your device before updating to iOS 9 (remember how I suggested making a backup?) then you can restore your device from that backup. If you don't have a backup then all is not lost. Just make a backup of your device in iTunes, then restore from that backup. It seems that if you only do iCloud backups and don't have access to a computer running iTunes then you're outta luck as far as this fix goes.
- Breathe a sigh of relief when it's all over.
It appears to be older iPhones -- specifically the iPhone 4s -- that are affected by this bug.
It's hard to judge how widespread this issue is, but given that Apple went through a beta program, not to mention that it controls the hardware so closely, failures like this reflect pretty badly on the company, and will undoubtedly raise concerns that quality is slipping.