Apple has announced that it has stopped signing iOS 16.3.1, making it impossible for iPhone users to downgrade to that version. This means that the only versions of iOS that can now be installed on an iPhone are iOS 16.4 and iOS 16.4.1, as well as the iOS 16.5 beta. Apple routinely stops signing older iOS releases over time to prevent users from downgrading to outdated software versions.
iOS 16.3.1 was released in February 2023 and was a minor update with bug fixes, security improvements, and additional Crash Detection optimizations for iPhone 14 models. However, Apple has now stopped signing it, which means that users who are already running a newer version of iOS cannot revert to it.
Apple released iOS 16.4 on March 27, 2023, with dozens of new emojis, notifications for web apps, Voice Isolation for cellular calls, and other enhancements. iOS 16.4.1 was released on April 7, 2023, with important bug fixes and security updates. One of the patched exploits allowed third-party apps to execute arbitrary code with kernel privileges, while a second exploit found in WebKit, the Safari engine, could also lead to malicious code execution.
For both flaws, Apple says it is “aware of a report that this issue may have been actively exploited,” so it is essential to install these updates as soon as possible to be on the safe side.
While downgrading to iOS 16.3.1 is no longer possible, users can still downgrade from iOS 16.4.1 or iOS 16.4 to iOS 15.7.4, which Apple is still providing security updates for. However, users who want to downgrade an iPhone or iPad must do so using a Mac or PC.
It’s worth noting that users running iOS 16.5 beta can also downgrade to iOS 16.4.1 or iOS 15.7.4. However, iOS 16.4 will likely be unsigned later this month, so iPhone users who wish to downgrade to that version have limited time remaining to do so.
Apple’s decision to stop signing iOS 16.3.1 is part of its effort to ensure that people can’t install an older version to take advantage of a security flaw. Additionally, it aims to make sure that as many people as possible have access to the latest APIs and features to allow apps to take advantage of them.
Apple will soon unveil iOS 17, a much bigger software update, during the WWDC23 opening keynote on June 5. If Apple follows the release cadence that we’re used to, we can expect months of betas through the summer before iOS 17 is finally made available to the public in or around September. Apple will also release big new software updates for the iPad, Mac, Apple Watch, and Apple TV at the same time.