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How to Install / Upgrade: Apple stops signing iOS 26.5.1 after critical security fix release

By Dillip Chowdary • Jul 21, 2026 • Source: 9to5Mac

Apple has stopped signing iOS 26.5 and iOS 26.5.1 following the release of a critical security fix for iPhone last week. This change prevents users from downgrading their software to iOS 26.5 or iOS 26.5.1 from newer software releases.

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To upgrade your iPhone to the software release with the critical security fix, install the newer release available for your device. Complete the update directly to a newer release, as Apple no longer allows installing or restoring to iOS 26.5 or iOS 26.5.1.

A key gotcha is that once you update to a newer release, downgrading back to iOS 26.5 or iOS 26.5.1 is impossible because Apple is no longer signing those versions. To verify your setup, check that your iPhone is running a newer release rather than iOS 26.5 or iOS 26.5.1.

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