Apple has renamed its iPhone bootloader from 'iBoot' to 'mBoot' in the second iOS 26.4 developer beta. This marks the first name change since iOS debuted nearly two decades ago, representing a significant departure from the long-standing naming convention.

The bootloader version number also jumped dramatically from 13822 to 18000, an unusually large gap that suggests potential architectural changes. The rebranding appears alongside other iOS 26.4 beta features, including end-to-end encrypted RCS texting with Android devices. Apple has not commented on the change, and the company rarely discusses bootloader modifications.

For most iPhone users, the renamed bootloader likely won't produce visible changes since iBoot primarily handles authenticated system boot and kernel verification. However, the dramatic version jump and name change could signal upcoming hardware or software changes, possibly related to Apple's expected March 4 product announcements. The new 'mBoot' designation appears in im4p files and can be spotted on Apple Silicon Macs running macOS 26.4 beta 2.