Type a particular string of characters into an iMessage and send it to someone else, and strange things could happen. We’ve seen these accidental discoveries time and time again in the past when users found character combinations that would render an iPhone useless. Apple is typically quick to patch these bugs and has done it again, this time with an issue that Google researchers discovered. Received in iMessage, a specific set of characters can do the unthinkable to your iPhone, and that is to brick it, locking you out of everything on it. The only fix is a factory reset and there’s no way to recover lost data that wasn’t backed up.

Project Zero researcher Natalie Silvanovich discovered the bug in mid-April, explaining that it only affects iOS devices:

On a Mac, this causes soagent to crash and respawn, but on an iPhone, this code is in Springboard. Receiving this message will case Springboard to crash and respawn repeatedly, causing the UI not to be displayed and the phone to stop responding to input. This condition survives a hard reset, and causes the phone to be unusable as soon as it is unlocked. The only way I could find to fix the phone is to reboot into recovery mode and do a restore. This causes the data on the device to be lost though.

You can’t do anything once you’ve received the text on iPhone running iOS versions earlier than iOS 12.3. Similar bugs in the past could significantly slow down a phone or crash the Messages app, but you could fix the problem in most cases without losing any data.

This time around, you’d have to go for a complete factory reset, which means that any data that hasn’t been backed up to iCloud or a computer will be lost. And when you do set up the phone for the first time, you’ll need to remove the SIM card and kill Wi-Fi to deal prevent the issue from recurring:

1) wipe the device with ‘Find my iPhone’
2) put the device in recovery mode and update via iTunes (note that this will force an update to the latest version)
3) remove the SIM card, go out of Wi-Fi range and wipe the device in the menu

The good news is that Apple patched this issue in iOS 12.3, which means that you’re safe as long as you’ve updated to the latest stable iOS release, or if you’re on an iOS 13 beta.