Apple closes the door on downgrading iPhone from iOS 26 to iOS 18

 iPhone users who upgraded to  iOS 26 can no longer revert to the previous version of iOS. Apple has closed the validation or signing process for iOS 18.6.2. 

This can be seen from the details of the installation files that are in the "signing" process within the Apple ecosystem, which is the operating system validation process carried out directly by Apple servers. 

Every time a user wants to install or update iOS (whether upgrading or downgrading), the Apple server checks the installation file (IPSW) used first. 

If Apple's servers are still "signing" the iOS version, then it can be installed on the user's device.

Now, with the end of the iOS 18.6.2 signing process , users who have already installed iOS 26 can no longer downgrade to iOS 18.6.2.

With this policy, users who have updated to iOS 26 can no longer go back to iOS 18. 

Meanwhile, users who are still using iOS 18.6.2 and have not upgraded to iOS 26 can still use their devices. 

However, these operating systems will no longer receive security updates or feature enhancements, leaving devices vulnerable to security vulnerabilities and potential app compatibility issues. 

iOS 26 itself was released on September 15, 2025, for iPhone 11 through iPhone 17, as well as the iPhone SE. Less than two weeks after its release, Apple left iOS 26.0 as the only version still "signed" and installable.

A similar policy applies to iPadOS and tvOS. Apple has stopped signing iPadOS 18.6.2 and tvOS 18.6.2, leaving iPad and Apple TV users with the option of using older versions of the OS without security support or upgrading to the latest version. 

Besides the new name, iOS 26 also brings major updates and feature enhancements. Some of the key new features in iOS 26 include the Liquid Glass design, Adaptive Battery Mode, and new ringtones.

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