Read these notes before proceeding
In order to downgrade to the previous major version (e.g. iOS 10 to iOS 9), important and regular action must be taken. For the downgrade to work, you must be proactive and prepare for a problem. Namely:
- Archiving backups
- Restoring the
.ipsw
file
Without regular attention to the two steps above, it may not be possible to truly downgrade the iOS version.