dfu

Saw the notification that Mac OS Tahoe 26.2 was available for update. So I did. But the update didn’t fully complete with the startup progress bar stuck at around 33%.

So I powered down and restarted. My MacBook Pro M3 was then looping at startup seeing the Apple logo then a black screen then the Apple logo again and repeat. Holding down the power button, my Mac showed an exclamation point with the URL support.apple.com/mac/restore. This was getting serious.

This is the first time I had to enter DFU mode and couldn’t get the key combo correct. Instead, follow these directions by Mr. Macintosh to enter DFU mode by holding Control, Option, right-sdie shift, and power for 10 seconds then let go of Control, Option, and right-side shift. Keep holding the power key, and this pattern got me to DFU mode.

With a second Mac, I tried reviving my busted Mac and that failed. I changed USB-C cables and ports and still no luck. I think this MBP DFU port is nearest the MagSafe plug on the left side of the keyboard. I deleted big files from my functioning Mac to create space to save the recovery startup files. I also installed the Apple Configurator app from the App Store. This is a more refined interface to restore/recover Apple devices. 

Reviving didn’t work so I went for a restore which does a factory reset of the Mac first. My Time Machine backup was about 2 weeks old but better than nothing. After several hours, my MacBook Pro was back (albeit with two weeks old data).

Who knows what caused all of this but before you install the 26.2 update, I would trigger a Time Machine backup and also restart your Mac before updating.