iOS 10.3.1 is now available to download. But here's how you can downgrade iOS 10.3.1 to either iOS 10.3 or iOS 10.2.1 on iPhone and iPad.
Downgrade iOS 10.3.1 Now if You Want to Go Back to iOS 10.3 or iOS 10.2.1
Apple released iOS 10.3.1 just yesterday which looks like a small release at face value but packs a lot of security related changes under the hood. Basically, if you care about security a lot, then this is one update you should not miss out on. But, I'm certain there are still going to be people out there who might not share the same thoughts. If so, then you might be considering to roll back to either iOS 10.3 or iOS 10.2.1 for any reason which you might have. Check out the tutorial below on how to do so.
Note: Downgrades are possible as long as Apple is signing a particular firmware release. Once the signing window is closed, there's no way to downgrade a device at all. At the moment, Apple is signing both iOS 10.3 and iOS 10.2.1, making the downgrade from iOS 10.3.1 possible. Also, it should be made abundantly clear that backups created on iOS 10.3 or above will not work on iOS 10.2.1, as Apple has changed its filesystem to APFS.
2. Download and install iTunes on your computer if you haven't already. Go to apple.com/itunes in order to do so.
3. Connect your iPhone or iPad to your PC or Mac using a Lightning USB cable and launch iTunes.
4. Once iTunes has completely loaded up, you will see your device appear at the top left hand corner of iTunes. Click on it to open.
5. Assuming you are done downloading iOS 10.3 or iOS 10.2.1 firmware files, click on the 'Restore iPhone' button in iTunes while holding down the left 'Shift' key (Windows) or the left 'Option' key (Mac).
6. A new window should come into view asking you for a firmware file. Select the one you downloaded in step 1.
7. The downgrade process will now begin. So please, at this point, do not touch your device at all. You want things to go through as smoothly as possible.
Once the process is complete, your iPhone or iPad will boot into the iOS welcome screen, ready to be set up like brand new.
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