New in the latest macOS Tahoe update: slight chance of total system failure

Did you know that one Mac can be used to "revive" a second Mac that's had its system firmware damaged? I didn't.

I learned about it this evening, when Shannon and I discovered first-hand that system firmware can be damaged in "rare circumstances" like...clicking accept on the system prompt asking her to install an update to the operating system she relies on to do her job.

It turns out there's a hidden jumpstart utility built into Finder that pops up when you connect your healthy Mac to a struggling one via USB-C cable. Like all things Apple, it just works. And by "just works" I mean works when using a specific port, after performing the needlessly-complex keyboard shortcut incantation required to lull it into DFU mode. The tool then offers to either "revive" or "restore" the connected Mac.

I'll spare you the details: it failed.

Now, Shannon is tech savvy and keeps no files locally that aren't backed up elsewhere. So all she's really losing here is time—which is bad enough. But it should not be possible for a normal user in normal circumstances to cause catastrophic system loss through the installation of a routine system update.

That's what makes this so appalling. This wasn't a big upgrade from Sequoia or a beta or anything like that, we're talking about a simple point to point update of Tahoe. This machine was literally provisioned last week and set up from scratch with no betas or cruft from old backups. You couldn't ask for a cleaner set of circumstances. If Tahoe falters here, what's it doing elsewhere?

As someone who's always struggling to convince friends and family to cultivate good software update habits so they can benefit from the latest security and usability improvements, all I can do is shrug and laugh at how profoundly Apple's latest software releases undermine my efforts.

I suppose it's our fault for expecting that "software update" implies "software improvement". Good grief.