Where and how can I obtain the relevant file to revert to iOS 8.4.1 I did not use iTunes as a backup but iCloud. Help much appreciated.
EDIT: With the release of iOS 9.02 on September 30, Apple stopped signing off on iOS 8.4.1. Users can no longer upgrade or downgrade to those versions of iOS using iTunes.
Read this entire post before just clicking the links and starting.
The downgrade is relatively easy, but if you have no idea what you are doing around Apple devices or computers, then with respect it's probably best to just wait a few weeks for iOS 9.1 and the new GO app. Hopefully they play well together for most people.
To downgrade from 9.0 or 9.01, you need a copy of the Apple operating system. It's an ipsw file. I got mine here because I wanted 8.4.1. Note that some computers might show the downloaded file as a zip file. If yours does, don't unzip it. Just change your folder settings to show file extensions if they are not showing already, and then change the extension from .zip to .ipsw
Download iOS 8.4.1 Final For iPhone, iPad, iPod touch [IPSW Links] | Redmond Pie
Just scroll down and use the link for your device. The ipsw file (iOS) is large file, so it will take a long time to download. Do not try to download the file to your mobile device. Download to a computer desktop or laptop.
Note: most people will have previously backed up their device on 8.4.1 before they upgraded to 9.0. If you
did not previously back up while on 8.4.1, the downgrade might work more smoothly for you (less chance of app or data loss) if you instead downloaded the ipsw file that matches the iOS you were on when you last did a backup. That way it's easier to restore if you need to restore once you downgrade from 9.0. You can't restore from a backup done on a newer iOS to a device with an older iOS which you will have once you downgrade from 9.0 to something else.
If you do not already have a backup done on 8.4.1, do a google search for the ipsw (iOS) version you need to match your latest backup. Using an iOS older than 8.4.1 only works if you have a jail broken device since Apple currently only signs off on 8.4.1 and later. Non jail broken devices can still downgrade to 8.4.1 but nothing older.
Once you have the ipsw file that matches your latest backup, follow directions from here. There are always risks, so I recommend this site because it mentions the warnings that other sites don't always mention.
How to Downgrade from iOS 9 Back to iOS 8.4.1 | OSXDaily
It is very fast after the large ipsw file downloads. Of course, things are different for everyone so be careful okay.
Last note: this only works as long as Apple continues to sign off on 8.4.1. That is the oldest they currently sign off on, and they can stop signing off on it at any time in the next couple of weeks. After they stop signing off on 8.4.1, you won't be able to downgrade from 9.0 or 9.01 unless you have a jail broken device.
