February 1, 2026
Plug, pray, repeat
Apple's MacBook Pro DFU port documentation is wrong
Mac ports play musical chairs; users fume while commenters split: Apple right or author wrong
TLDR: A Mac user says Apple’s guide mislabels the special rescue port, breaking external macOS updates, while others claim it’s a separate setup or firmware quirk. Commenters split between “docs are right,” hardware theories, and veteran booters rolling eyes—important because one wrong port can burn hours.
Apple’s own guide says certain MacBook Pro models have a special “DFU” port — a rescue plug used for deep firmware fixes — and to avoid it when installing macOS on an external drive. One developer says that doc is wrong for their 16-inch M4 Pro, claiming the magic port is on the opposite side and that this mix-up sabotaged days of failed updates. Cue the comment cage match. Skeptics like AceJohnny2 argue the author never actually tested DFU mode, so pinning the mess on Apple’s guide is a reach. Meanwhile, tgma swears the docs are correct, having done DFU “many times.” In the popcorn gallery, vlovich123 spins a hardware mystery: maybe that port is hardwired straight to the firmware brain, skipping normal checks — hence the weird behavior.
Old-school tinkerers jump in with “this isn’t DFU, it’s firmware boot logic” vibes, with pvtmert insisting it’s about how the machine talks to ports during installs, not Apple’s secret port map. The memes write themselves: “left port vs right port,” “port roulette,” and “plug into the vibes.” The author also found that macOS security settings for external drives can block updates unless you tweak them via Recovery — a gotcha that had folks linking Michael Tsai’s posts and the Apple support doc. Verdict? The community is split between Apple docs are fine and this port thing is chaos.
Key Points
- •Apple’s DFU port identification guidance conflicts with observed behavior on a 16-inch MacBook Pro with an M4 Pro chip.
- •External macOS installation/update on Apple silicon requires avoiding the DFU port; port choice impacted the author’s update attempts.
- •Updating an external SSD from macOS 15.2 to 15.7.3 repeatedly failed via both GUI and CLI without informative errors.
- •Following Michael Tsai’s guidance, setting the external drive as the startup disk enabled changes to security policy (LocalPolicy).
- •The author suggests both fixing LocalPolicy and switching to a different USB-C port were necessary to complete the macOS update.