Apple no longer signs iOS 15.4.1, downgrade and restore blocked

Following the launch of iOS 15.5 on May 16, Apple has stopped signing iOS 15.4.1, the previously available version of the operating system that was released in late March. As iOS 15.4.1 is unsigned, it is not possible to downgrade to this version after installing iOS 15.5. Ditto if you want to restore. This also applies to iPadOS 15.4.1.

Why does Apple block old firmware?

Apple routinely stops signing old firmware after new updates are released to encourage customers to keep their operating systems up to date. It is therefore not surprising that iOS 15.4.1 is no longer signed.

For jailbreak enthusiasts, this does not change anything because the flaws being exploited are limited to iOS 15.1.1 or even iOS 15.3.1 in the best case.

ios 15

The recent innovations of iOS

iOS 15.4.1 was a minor update that fixed an issue that could cause the iPhone battery to drain faster after the launch of iOS 15.4. But we had seen that this problem was only really corrected with iOS 15.5 which increased the autonomy. It also fixed an AppleAVD issue that could allow an application to execute arbitrary code with kernel privileges, an issue that Apple said was being actively exploited.

iOS 15.5 added an Apple Cash feature to request and send money (for US), as well as new features for the Podcasts app and a fix for an issue with HomeKit automations. It also includes several security updates, and those who haven’t upgraded to iOS 15.5 yet should do so for this reason.

Apple also stopped signing tvOS 15.4.1 and HomePod 15.4.1 software to Apple TV and HomePod, respectively.

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