Apple is no longer signing iOS 26.5 and iOS 26.5.1, preventing downgrades to these software versions from newer releases. The move comes after a critical security fix was issued for iPhone last week.

Apple regularly cuts off versions of iPhone software after newer updates become available. The company stops signing releases once updates are proven to be generally free of major issues.

In the case of iOS 26.5.1, Apple released iOS 26.5.2 on June 29. Apple gave the release a full week in the wild before closing the door on iOS 26.5.1.

Apple flagged iOS 26.5.2 as an important software update for security vulnerabilities.

The company even moved forward with some fixes planned for iOS 26.6 to give customers the most secure software sooner. AI-powered hacking risks were cited as the reason.

iOS 26.5.2 is the latest version of iPhone software. iOS 26.6 beta 4 arrived yesterday for developer testing alongside iOS 27 beta 3.

Source: 9to5mac