Restore an iPhone from iCloud backup of newer iOS version
You cannot downgrade unless one of the following is true:
- Apple is still signing installations of the previous version of the OS to which you wish to downgrade, or
- Your phone is jailbroken, you have saved your SHSH blob from the prior version, and you have a way to run a replay attack with that SHSH blob to trick the device into believing Apple is still signing that version.
You can determine whether a particular version of iOS is currently being signed for a given device on ipsw.me. Simply change 8.2 in the URL to the version you want to check, such as 8.0 or 8.3.
This list of updates, from the same website, shows when Apple starts and stops signing a given version.
In your case, 8.2 stopped being signed on 5/4/15. Therefore it is no longer possible to downgrade. Generally the window is about a month or so after a new version is released.
If you go to the folder that the backup was made there is a list of different coded long numbered folders there, use the list of the available iphone backups to determine the backup you want to restore. Inside that folder there will be an info.plist file open it with a text editor. It will have the version of the IPSW in that file. Search for "Product Version" and you should be able to find a string below with the version number of that backup. Edit that number to the version of the device you want to restore to and save the file. Then the backup should show up in itunes and you will be able to restore this backup to your device with an earlier IOS version.
Product Version 8.3
Keep in mind this is experimental.
I just got around this problem.
- Setup the phone as a new phone, not from backup.
- Go to General > Updates and update to iOS 8.3
- Go to General > Reset and Reset all Data and Content. This will keep the iOS version on the as 8.3.
- Now you can setup the phone and restore those new backups!