All changes between the first and second beta versions are listed on the Github account “blacktop”. The surprising change can be found under “iBoot”: While iBoot-13822.100.791.502.1 appeared in the first beta of iOS 26.4, the second beta used mBoot-18000.100.10.0.1 – without any further explanations. Apple does not mention the change in the release notes.
Is Apple introducing new hardware?
The change is also surprising because Apple has previously taken the opposite path: When Macs integrated the T2 chip, iBoot came from mobile devices to the Mac. The switch to Apple Silicon finally cemented this change. iBoot is used during the startup process in iOS and iPadOS as well as macOS, as well as in peripheral devices such as Apple TV. The sudden change is not limited to mobile systems – apparently the second beta of macOS 26.4 is also switching from iBoot to mBoot.
The T2 controller brought iBoot to the Mac for the first time.
The sudden change suggests a change in the boot process. Their origin could be purely cosmetic, but could also be based on the idea of new hardware. Since Apple has invited some journalists to an “experience” in three locations on March 4th, this change adds further fuel to expectations that Apple will unveil new devices on this date. Rumor has it that five new products will come onto the market at the beginning of March: In addition to MacBooks and iPhone 17e and new iPads, a new generation of Studio Display would also be conceivable, as would a new Mac Studio. There is currently no word from the rumor mill about new HomeKit devices, such as the long-awaited HomePad.