Following the release of iOS 12.1 on October 30, Apple has stopped signing iOS 12.0.1, the previous version of iOS that was available to consumers.
iPhone, iPad, and iPod touch owners who have upgraded to iOS 12.1 will no longer be able to downgrade to iOS 12.0.1. The iOS 12.1 update was significant, introducing Group FaceTime, eSIM support for Apple's newest iPhones, new emoji, and more.
Apple routinely stops signing older versions of software updates after new releases come out in order to encourage customers to keep their operating systems up to date.
iOS 12.1 is now the only version of iOS that can be installed on iPhones and iPads by the general public. Developers and public beta testers can download iOS 12.1.1, an iOS 12 update that's currently being beta tested.
Top Rated Comments
Just search on Google about installing a beta profile of tvOS 12 or WatchOS 5 on your iPhone. Once you’ve installed the beta profile of tvOS or WatchOS, you won’t be prompted to update, theoretically. For some people it fails to work, but usually it is pretty effective; your iPhone/iPad will tell you that your software is up to date.
iOS 12 is fine (so far). Other than jailbreaking, no one wants to go back to iOS 11. But older versions of iOS? Older devices? HELL YEAH people want to downgrade.
The speed difference on an iPhone 4S or an iPad 2 running iOS 7.1.2 versus iOS 9.3.5 is INSANE.
There are some methods for some devices that let you downgrade, but it's usually messy. I have iOS 6.1.3 on my iPad 2, and iOS 8.4.1 on my iPhone 4S. I would have iOS 4.1 on my iPhone 3GS, but its charge port isn't working right (it charges, but no longer interfaces with a computer).