MacBook suddenly stopped working after the update to macOS 26.4.1

Your MacBook won’t boot after the 26.4.1 update. Why a DFU restore fails with error 4042 and how to recover the machine with a double revive without losing data.

The symptom — and its variants

The MacBook won’t start up after a macOS 26.4.1 update. In the shop we see this in several variants:

The customer manually ran the 26.4.1 update, rebooted, and hit a black screen.
The update installed automatically overnight (macOS default: “Install tomorrow at 2 AM”). Next morning, the machine no longer boots.
The customer never clicked Update — but automatic firmware or security updates land the same way.

Visual symptoms vary: fully black screen, Apple logo followed by black, fans spinning with no display, power LED on with no video, or an endless reboot loop. Many customers arrive certain they didn’t update anything — automatic updates often make the install invisible.

What’s actually happening

On affected models the 26.4.1 firmware triggers a kernel panic during the DFU-restore transition phase. The firmware write completes cleanly, but as the device tries to hand off from DFU to a booted recoveryOS, it panics — and never re-enumerates.

The log — error code 4042

A typical excerpt from Apple Configurator 2:

[17:59:01.7501] Finished DFU Restore Phase: Successful
[17:59:01.7505] Changing state from 'Restoring' to 'Transitioning'
[17:59:01.7505] Creating timer to monitor transition
[17:59:01.7505] Creating a timer for 10 minutes
[17:59:01.8554] DFU mode device disconnected
[17:59:01.8554] Device disconnected during transition
[18:09:01.7592] Timer fired to timeout transitioning device
[18:09:01.7596] Changing state from 'Transitioning' to 'Disappeared'
[18:09:01.7596] Device disappeared during transition
[18:09:01.7597] Device isn't booted but USB is up.
[18:09:01.7655] Restore completed, status: 4042
[18:09:01.7655] Elapsed time (in seconds): 607
[18:09:01.7655] Failure Description:
[18:09:01.7655] Depth:0 Code:4042 Error:Gave up waiting for device to transition from DFU state to DFU state.
[18:09:01.7664] AMPDevicesAgent: Restore error 4042

In plain language: the firmware write was successful. The device disconnected — as expected — to reboot into recoveryOS. It never came back within the 10-minute window. Configurator gave up and reported 4042. The root cause is neither a bad cable nor a failed write — it is a kernel panic at boot that leaves the device in a dead in-between state.

The safe fix — “Double Revive”

Important warning up front: do not attempt a full Restore. Restore erases all user data and hits the same 4042 because the target firmware is the broken 26.4.1.

The safe path in Apple Configurator 2:

Put the device into DFU (the usual model-specific keystroke sequence).
Revive (not Restore!) using an older IPSW — one version back, e.g. 26.4.0 or the latest 26.3.x. Revive reinstalls firmware and recoveryOS only; user APFS volumes are untouched.
The device now boots normally on the older firmware. Wait for the login screen.
Revive again — this time with the current IPSW (26.4.1). This second revive succeeds because the device is alive and does not have to make the firmware transition out of a cold DFU boot.
Data preserved; machine is on current firmware.

Why it works: the first revive restores the device to a bootable firmware that does not trigger the kernel panic on the transition path. The second revive upgrades firmware from a running system, bypassing the broken cold-boot path entirely.

What NOT to do

Do not Restore in Configurator — data loss and the same 4042 error.
Do not pull the cable while the device is stuck in “Transitioning” — the risk of a deeper brick goes up sharply.
Do not use third-party tools for Apple-Silicon firmware work. There is no credible alternative to Configurator for this.

When to bring it to us

This is a safe in-shop fix we do regularly. Data stays intact, the repair usually takes less than an hour. Contact us and book a slot.