Apple has ceased signing iOS 16.3.1 and iPadOS 16.3.1 after the release of iOS 16.4 and iOS 16.4.1 updates over the last two weeks. This means that users of iPhones and iPads are no longer able to downgrade to the older operating system version if they have already upgraded to a newer version of iOS.
The iOS 16.3.1 version was launched on February 13th, with bug fixes, improved Crash Detection for the iPhone 14, and security patches. Subsequently, Apple released iOS 16.4 on March 27th, featuring numerous new emojis, web app notifications, Voice Isolation for cellular calls, and other improvements.
The iOS 16.4.1 update, which was released to the public on April 7th, contains "important bug fixes and security updates." One of the fixed exploits allowed third-party applications to run arbitrary code with kernel privileges, while a second exploit identified in WebKit, the Safari engine, could also result in malicious code execution.
For both vulnerabilities, Apple has acknowledged that "this issue may have been actively exploited" and urges users to install these updates as soon as possible to avoid any issues.
Reverting to older iOS versions is a common technique utilized by those who jailbreak their iPhones and iPads. In December, the hacker team palera1n created the first jailbreak tool based on the checkm8 exploit, which is compatible with iOS 15 and iOS 16. The tool is compatible with all versions from iOS 15.0 to iOS 16.3.
Reverting an Apple device to a prior iOS version can also be beneficial to users who encounter significant bugs after upgrading to the latest version of iOS.
