Except for when you agreed to the terms and conditions that explain that. Too many people are under the misinformed impression that when you pay for a device, its 100% yours. Sure- the devices is, but the operating system isn't. As is any software system- there are binding terms and conditions for usage. If you don't like them, android has a perfectly fragmented operating system you could try out (but then again, you might wanna watch out for more of those pesky Terms and Conditions!) And for the record- Apple does allow downgrades to previous versions (IE 11.2 back to 11.1.2). --- Post Merged, Jan 11, 2018 --- If iOS 11 was the root cause of this issue- EVERYONE would be having these problems. Correlation is not causation. The issue may have occurred after our update, but more than likely, its the installation of your update that caused the problems. Reinstalling is your best bet for a fix- but if you want to do it right, you need to avoid restoring a backup to your device (Otherwise you're just bringing the same corrupted files back to your device again).