Bizarre iPhone bug causes some audio messages to fail. Here's why

Super-weird bugs in Messages are nothing new, but this latest one is a real head-scratcher: If you try to send an audio message with the phrase “Dave and Buster’s,” it won’t work. Why would that specific phrasing cause a problem? A coding expert has cracked the case. I won’t say “and the reason will shock you,” but if you’re anything like me, you’ll find it interesting.

First, let me explain what happens when the bug triggers. At first, the audio message (“I’m off to eat lunch at Dave and Buster’s,” as an example) appears to send normally. It shows up in the Messages thread to the recipient, along with a transcript of the content. No problem is flagged.

It’s at the recipient’s end that we spot the issue. Initially the recipient sees the ellipsis icon, indicating that something is being typed or sent… but this carries on, and carries on, and eventually disappears. And at this point there is no indication that anything has been sent at all: no message, no message transcript, no message failed notification. In fact, if the recipient didn’t happen to have the app open, or had it open but was in a different conversation thread, they never would have known something was supposed to be on the way.

This bug is new to me, and the first time I heard about it was when it was discussed on Monday in the blog run by Guilherme Rambo, a coding and engineering expert. Rambo, in turn, heard about the bug on the Search Engine podcast, which devoted its May 9 episode to the subject.

Rambo reproduced the bug, guessed the problem must be at the recipient end, then plugged that device into his Mac and started looking at logs. And from that point it doesn’t appear to have taken long for him to work out what was going on: iOS’s transcription engine was recognizing the name of the U.S. restaurant chain, changing it to the correct corporate branding (“Dave & Buster’s,” with an all-important ampersand), and then passing that into the XHTML code used to send a transcript with the audio message. The problem isn’t being caused by the words Dave and Buster’s, but by the ampersand character between them, which has a special purpose in coding and prevents the code from being parsed correctly.

As you can see in the image at the top of this story, a seemingly successfully sent audio iMessage ending with the phrase “Dave & Buster’s” appears as sent but never actually appears on the recipient’s phone. After a while, the audio message disappeared from the sender’s phone, and the recipient was completely unaware that the message had ever been sent.

With that in mind, it’s a short leap to recognize that other brands could cause the same issue—they just haven’t been spotted doing so up to now. Rambo notes that “M&Ms” will do the same thing. For U.K. iPhone owners, in fact, “Dave and Buster’s” doesn’t trigger the bug because that chain is evidently not well enough known here and doesn’t get its ampersand added by autocorrect.

To reproduce the issue, I had to ask a friend to send me a message about the supermarket chain M&S. Sure enough, this caused the hanging ellipsis followed by an unsent message. At the time of writing, it seems almost certain that any phrase iOS would recognize as containing an ampersand would cause an audio message to fail, and when I put it like that, it’s surprising the bug hasn’t been more widely reported.

Karen Haslam / Foundry

On the plus side, one would imagine it’s a bug that should be easy to patch in an iOS update. The transcription feature in Messages simply needs to be told to “escape” special characters so they don’t mess up the parsing process. And as Rambo notes, this isn’t a bug with any security vulnerabilities; indeed, it shows Apple’s BlastDoor mechanism working correctly.

“Many bad parsers would probably accept the incorrectly-formatted XHTML,” he writes, “but that sort of leniency when parsing data formats is often what ends up causing security issues. By being pedantic about the formatting, BlastDoor is protecting the recipient from an exploit that would abuse that type of issue.”