Why an iPhone May Reboot After 72 Hours—and What GrayKey Preserve Claims to Do

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An iPhone that stays locked and is not unlocked for 72 hours may automatically reboot. That changes its forensic security state from After First Unlock (AFU) to Before First Unlock (BFU), making more data inaccessible to forensic tools until the passcode is entered. A leaked Magnet Forensics training video describes a law-enforcement feature called GrayKey Preserve that claims to retain the more accessible AFU state through a reboot. Its effectiveness, supported devices and iOS versions have not been independently confirmed.

What happens after 72 hours?

The reported behavior is an inactivity reboot: according to Magnet Forensics documentation and reporting from 404 Media, a device reboots if it has remained locked and has not been unlocked for 72 hours. The reboot changes the device from AFU to BFU. It is not the same as an iPhone being remotely locked, erased or disabled after failed passcode attempts.

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That timing also appears in an unrelated Apple feature. Apple Support says that on iOS 17 and later, after changing a passcode, a user can use the previous passcode for 72 hours to recover access. That is a passcode-recovery window—not the cause of the inactivity reboot.

Why the reboot matters to forensic access

AFU: unlocked since the last reboot

After First Unlock means the phone has been unlocked at least once since its most recent boot. Some encrypted data is then available to authorized forensic tooling, depending on the device, software and data involved. AFU does not mean the phone is unlocked for ordinary use or that all its data is exposed.

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BFU: not yet unlocked since the last reboot

Before First Unlock describes the state after a reboot and before the passcode has been entered. More data remains protected by encryption until the user enters that passcode. A reboot can therefore reduce the access available to forensic tools, even though it does not itself reveal or change the passcode.

Apple documents protections that limit access to protected data and escalating delays after incorrect passcode attempts. Those protections are separate from the reported 72-hour inactivity reboot; Apple has not endorsed GrayKey Preserve.

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What GrayKey Preserve is reported to do

404 Media reported that a leaked Magnet Forensics law-enforcement training video described a new device called GrayKey Preserve and an Evidence Preservation Mode for existing GrayKey hardware. The stated purpose is to capture or preserve an iPhone’s AFU state so it is not lost if the device reboots, loses power or undergoes memory maintenance.

A Magnet employee in the video, as quoted by 9to5Mac, said: “That AFU state is captured,” and that “even if that device does reboot for any number of reasons, memory maintenance or the power is lost or whatever, the AFU state is not lost.” The employee called this “the true magic behind the GrayKey Preserve and the Evidence Preservation Mode function.” Those are claims in a vendor training video, not findings from independent testing.

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What is known—and what remains unverified

9to5Mac reported that Apple and Magnet did not respond to its requests for comment. The reporting does not establish how long the capability has been available or whether it works with the newest iOS releases. The 72-hour timing is documented and reported for 2024–2026; no independent figure for how common the behavior is, or for the tool’s success rate, is established.

Does GrayKey Preserve bypass an iPhone passcode?

That is not what the training-video claim says. It describes preserving an AFU state, not defeating or removing a passcode. The distinction matters: keeping a forensic state from being lost after a reboot is different from unlocking a phone or guaranteeing access to its data. The feature is described in a law-enforcement forensic workflow, not as a consumer iPhone setting or service.

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