What really happened with Apple’s Face ID 'fail' onstage [UPDATED]

Craig Federighi, Apple’s senior vice president of software engineering, discusses features of the new iPhone X at the Steve Jobs Theater on the new Apple campus on Tuesday, Sept. 12, 2017, in Cupertino, Calif. (AP Photo/Marcio Jose Sanchez)

Update: The original theory in this story was incorrect. We have made updates based on information from Apple.

The internet is buzzing. As Apple (AAPL) demonstrated its new flagship phone onstage, the $999 iPhone X, the face-recognition unlocking feature failed. Bigly and splashily.

Apple software head Craig Federighi’s live demo had only just begun.

“Unlocking it is as easy as looking at it and swiping up,” he said, picking up the phone at his podium. “And—you know—“

The audience knew right away that something was wrong. Not because the phone didn’t unlock automatically and instantly, as it should have, but because Federighi seemed rattled.

He hit the Sleep switch to turn off the screen. “Let’s try that again,” he said.

No luck. “Ho ho ho! Let’s go to backup here!”

He picked up a second, backup demo phone. This time, the Face ID worked, and he went on with his demo.

But the headlines jumped to swift and merciless conclusions: Face ID had failed.

“Apple suffers embarrassing demo Face ID fail at iPhone X launch,” wrote the Telegraph. “Apple’s Face ID unlocking failed during its big demo,” said Business Insider. “Apple’s stock suddenly dropped after that Face ID fail,” went Vice.

Some of the stories describing a technology failure onstage.

In fact, though, Face ID performed perfectly. It appears somebody at Apple set up the phone incorrectly.

To see what really happened, just look at the screen Federighi was confronting. It says, “Your passcode is required to enable Face ID.”

Turns out, Face ID was performing exactly as designed.

Every iPhone owner has seen this screen. It’s the message you see when you restart your iPhone, rather than just waking it. If you wake your phone, you can unlock it with your fingerprint. But if it’s been off, you have to enter your password manually, every single time. (Same thing on Samsung phones, by the way.)

It’s a security measure, meant to prevent evildoers from hacking the phone to get your fingerprint data. “Your fingerprints aren’t actually stored in your iPhone,” explains Apple consultant Chuck Rogers on Quora. “The iPhone stores numerical representations of your fingerprints in something called the Secure Enclave. When you place your finger on the Home button/sensor, it compares the numerical representation of your fingerprint scan with what is stored in the Secure Enclave.

“Your passcode is required when you restart because it unlocks the Secure Enclave. Without entering your passcode at restart, your iPhone cannot recognize your fingerprint(s), because the Secure Enclave is not accessible until after you enter the passcode.”

Exactly the same system is at work on the iPhone X. You can unlock a sleeping phone with face recognition. But if the phone has been restarted or shut off, you still have to enter your password manually.

Somebody, in the process of setting up Federighi’s demo phone, had restarted it before the show. The “passcode is required” message protected Federighi’s stored face data, just the way today’s phones protect your stored fingerprint data.

Embarrassing? Yes. Foolish? Yes. Did the demo go as planned? No.

But did Face ID actually fail? No, it didn’t. In fact, it worked flawlessly.

[UPDATE: Commenters have noted that the “passcode is required” message doesn’t have the same wording as the one that you see, on a Touch ID phone, after a restart. Instead, it resembles the message you see when someone has tried Touch ID unsuccessfully too many times. If Face ID uses the same scheme, we can’t know who had tried it unsuccessfully—stage crew? keynote team member?—but it’s safe to assume that it wasn’t Federighi. If he had tried and failed before the show, he certainly would have insisted on troubleshooting the phone after the first failure. In other words, something went wrong, but it wasn’t Face ID misbehaving.

On the other hand, on MacRumors.com, commenter Cinetagonist notes that “That message appears if you don’t use your iphone for 5 hours — Touch ID (and Face ID) tokens are zeroed after five hours in non-use state, and you have to enter passcode to reenable the security feature. I bet that was the case on stage.” That’s fairly plausible, since several sources have told me that Apple reps were in that theater setting up all night.

Now, you also see that message if Face ID has failed to recognize you twice in a row. Some people are theorizing, therefore, that Face ID really did fail onstage—that Federighi tried three times to get it to recognize his face, and it failed all three times. I was there live, and I’ve studied the video, though, and he simply did not try three times. He tried it once—no response—then turned the phone off and on again, and that’s when the “passcode” message appeared.

In that Comments, let me know what you think!]

FINAL UPDATE: Tonight, I was able to contact Apple. After examining the logs of the demo iPhone X, they now know exactly what went down. Turns out my first theory in this story was wrong—but my first UPDATE theory above was correct: “People were handling the device for stage demo ahead of time,” says a rep, “and didn’t realize Face ID was trying to authenticate their face. After failing a number of times, because they weren’t Craig, the iPhone did what it was designed to do, which was to require his passcode.” In other words, “Face ID worked as it was designed to.”

More from David Pogue:

How Apple envisions life without a Home button

The $999, eyebrow-raising iPhone X: David Pogue’s hands-on review

iOS11 is about to arrive — here’s what’s in it

MacOS High Sierra comes this fall—and brings these 23 features

T-Mobile COO: Why we make investments like free Netflix that ‘seem crazy’

How Apple’s iPhone has improved since its 2007 debut

David Pogue, tech columnist for Yahoo Finance, is the author of “iPhone: The Missing Manual.” He welcomes nontoxic comments in the comments section below. On the web, he’s davidpogue.com. On Twitter, he’s @pogue. On email, he’s poguester@yahoo.com. You can read all his articles here, or you can sign up to get his columns by email.