Stephen Darlington ▸ "Preview" is damaged and can't be opened.

"This was the rather surprising error message that I’ve been getting when I try to open a PDF from the Finder since I upgraded to OS X Yosemite. It’s bad enough when you get an error message, but one suggesting that you delete a frequently used app is inconvenient to say the least!

"Since I found it, I’ve been using a workaround: start Preview.app and open the file manually.

"But there’s a better answer. Apparently it just has a duff “quarantine” attribute set. To get rid of it and get things back to normal simply do the following in a Terminal window"

There's a mysterious extended attribute that's being set on Preview, along with a couple of other Apple apps on 10.10, which keep it from working correctly. I wouldn't normally comment on something like this, but the OS is mentioning Acorn in its dialog, even if Acorn isn't installed on the system anymore.

I have no idea what's going on, or why Acorn is involved. I'm wondering if the bug causing this is choosing Acorn out of a list of applications and just grabbing the one off the top. And if the list is sorted alphabetically, that's Acorn's bad luck I guess.

If you've seen this dialog with another app mentioned in there, I'd love to know about it.