Crash Almost Any OS X App By Typing These Specific Characters

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Crash OS X Character String

An odd bug in OS X causes nearly any application to crash by typing in a short string of characters, according to a bug report published last Thursday and brought to our attention by tech site Neowin. Typing the world “File” (with a capital F), a colon, and three forward slashes will crash most apps on OS X Mountain Lion.

We had to log into our site’s backend via Windows to type the following string of characters because doing so on OS X crashed both our text editor and the Web browser we use to upload articles. Here it is:


It has been suggested that the bug is linked to OS X’s built-in spellchecker, but the crash occurs in locations that are not spellchecked, such as Chrome’s address bar. We’ve tested and verified that the bug occurs in TextEdit, Calendar, and even Final Cut Pro X. Third-party apps such as Chrome and Byword are also affected.

Although Safari crashes if we type the phrase into a text box on a Web page, it surprisingly did not crash when we typed it in to Safari’s address bar, although we’ve read reports from some users that claim that even the Safari address bar was affected for them.

The bug occurs on all versions of OS X 10.8 Mountain Lion, including the latest prerelease build of 10.8.3. Macs natively running previous versions of OS X were not available for testing but none our OS X virtual machines dating back to 10.5 Leopard were affected when virtualized by VMware Fusion.

Apple has been notified of the bug and should hopefully have a fix soon. Although the string of characters is not a common one that many users are likely to type, it may be cause for mischief or a point of attack by those coding software with malicious intent.

Those who wish to attempt to recreate the bug are free to do so by typing the phrase into nearly any OS X application. The only recommendation is to save any important documents or files first, as our testing shows that few apps stand a chance against crashing.

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Surprisingly, doesn’t crash.

Mário Pereira

Even in my Safari address bar the bug make it crash.
It is kind of funny, because is not that I’m going to write this in a normal conversation! :p


How about saying “Mountain Lion” in the headline, or at least toward the top, so you don’t waste the time of the millions running something else?


Caused Notes to hang and Reminders to crash. Caused Safari to hang, but not crash out.


Also causes the Finder to crash if typed into Spotlight.


Caused TextEdit to crash and then caused the report to Apple to crash.

A Programmer

Even worse - if you open a file containing that character sequence in TextEdit (or other Cocoa apps) they will crash.
This is why Problem Reporter crashes when it tries to display the problem (as it’s in the crash log).

It’s not actually the spellchecker.
It’s the data-detectors (which make URIs etc. clickable).
It’s a Cocoa programming error & potentially an exploitable security issue.


I wonder what changed in data detectors between Lion and Mountain Lion?


Crazy… can easily crash mac web browsers by populating text fields with this (I just tried it and it crashed Safari). I wonder how long this will take to get fixed…

Bryan Chaffin



Can’t resist what Bryan? The urge to send a File:/// to every user you know smile, I wonder how many people subscribe to comments? A potential f:///bomb maybe?


@ 1stplaceuser:

Not that surprising as data detectors obviously can’t parse the terminal.



This will be fixed with probably one line of code.  Better get started sending your emails.  And if anyone should open one, well, they may have to restart their email.  Oh, the horrors!

Bryan Chaffin

Ah, I was referring to my overwhelming need to try it myself, Droid. Turns out it works. smile


This was a fun trick, but it crashed reminders and now it crashes every time I open it. Is there any way to edit the reminder via some obscure system file? Or maybe just a way to reset/reinstall reminders?


Okay I found the place where the reminders are stored
and I deleted the reminder with F i l e : / / /  but it still doesn’t work. I then tried changing the text in that certain reminder, but that didn’t fix it either. Any Help?

Jim Tanous


I’m sorry to hear you’re having trouble. I’ve attempted to recreate your issue but I’m not experiencing the same problems. Reminders on 10.8.2 does crash when I enter the phrase, but the app reopens without issue and my entry with the phrase is gone.

Are you creating the reminders in a local “On My Mac” category or via an iCloud account? If it’s an iCloud account, has the entry been pushed to iCloud or another device and is it being synced back when you reopen Reminders, thus causing the crash again?


Jim: I would think it’s local. I haven’t ever used iCloud, and I didn’t change any settings for reminders. And I don’t have any other current Apple devices either. I’m on a new Macbook Air, OS X 10.8.2. When I try to open reminders, it doesn’t “crash”; it shows up on the dash, and if i click the icon enough, I see a thin outline the size of the normal reminders window. It looks like the shadow from the window, but the area where the window would be is transparent. I have another friend who is experiencing the same problem (He is the one who showed me the trick.) He apparently didn’t think it important to tell me to not try it in reminders. And also thank you for trying to help.

Jim Tanous

Hi Ben,

Topher Kessler over at CNET put up some troubleshooting steps for solving issues related to the bug.

Give those a shot and let us know if they work for you.


This lends some credibility to Jeff Goldblum’s ability to crash the mothership with a PowerBook 5300! Talk about your achilles heel! (or thermal exhaust port!)

(I gotta figure out how to properly add URLs)




You have just revealed the tip of the NSA’s vast iceberg for crashing enemy networks in the event of full scle cyberwar.  Expect a visit from men in black arriving in unmarked black helicopters in the middle of the night!


Lol, the one time that Ableton Live won’t crash is when you type this.

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