Some Mac App Store Apps 'Damaged' Due to Expired Security Certificate
A growing number of MacRumors readers and Twitter users have been experiencing an issue with some Mac App Store apps displaying a "damaged" error when opened since late Wednesday. The issue has affected popular apps such as 1Password, Acorn, Byword, DaisyDisk and Tweetbot.

Mac users are prompted with this error message when opening Mac App Store apps:
“App Name” is damaged and can’t be opened. Delete “App Name” and download it again from the App Store.
Tweetbot developer Paul Haddad tweeted that the issue appears to be related to security certificates that expired on November 11, 2015, and he further speculated that the receipts now using SHA256 encryption may be causing problems with older OS X versions.
The issue, however, also appears to affect some users running OS X El Capitan, leading Haddad to believe that Mac App Store apps contacting Apple's servers simultaneously may be causing a "self inflicted DDOS on Apple’s receipt generation service."
Haddad says that rebooting your Mac on OS X 10.10 or later may resolve the issue, while some users have been forced to reinstall apps from the Mac App Store, disconnect from and reopen the Mac App Store or simply reenter their Apple ID password.
It appears that Apple has since set a new 2035 expiration date for the security certificates, per The Guardian, at least some for apps, but the issues are persisting for some. Apple did not respond to request for comment.
Update: Rene Ritchie at iMore has further explained what's causing Mac apps to report as "damaged" and what can be done about it.
Popular Stories
While the iPhone 17 Pro and iPhone 17 Pro Max are not expected to launch until September, there are already plenty of rumors about the devices.
Below, we recap key changes rumored for the iPhone 17 Pro models as of March 2025:
Aluminum frame: iPhone 17 Pro models are rumored to have an aluminum frame, whereas the iPhone 15 Pro and iPhone 16 Pro models have a titanium frame, and the iPhone ...
Apple regularly refreshes the MacBook Pro models, and a new version that uses M5 series chips is in the works. Apple just finished refreshing most of the Mac lineup with M4 chips, and now it's time for the M5. Rumors suggest that we could see the first M5 MacBook Pro models this fall.
Design
There have been no rumors of a design update for the M5 MacBook Pro models that are coming this...
Apple is going all out with promotions for the popular Severance Apple TV+ show today, and as of right now, you'll find a new "Lumon Terminal Pro" listed on Apple's Mac site.
The Lumon Terminal Pro is designed to look similar to the machines that Severance employees like Mark S. and Helly R. use for macrodata refinement. The Terminal features a blue keyboard, a small display with wide...
In the mid-to-late 2000s, Facebook was all about staying connected with friends and family. However, as the social media platform added new features and grew over time, that core experience began to get drowned out.
That changes starting now, according to Meta, which today introduced a new feature that will "bring back the joy" of classic Facebook.
Specifically, Meta has redesigned the...
Apple is expected to release iOS 18.4 to the general public as soon as next week, following more than a month of beta testing.
Apple's website says some iOS 18.4 features will be released in "early April," so the update should be out as early as Tuesday, April 1.
Apple this week seeded the iOS 18.4 Release Candidate, which is typically the final beta version, barring the discovery of any...
Update 7:25 pm: Based on comments from our forums, it appears the original Weibo post may have been mistranslated and "8K" actually refers to the high price of the device rather than 8K video recording capabilities. The iPhone 16 Pro currently starts at 7,999 yuan in China.
Our original article follows below.
Apple's forthcoming iPhone 17 Pro models are capable of shooting 8K video, up...
Last week, we covered a report claiming that Apple's book-style foldable iPhone (or "iPhone Fold," as we are provisionally calling it here) will use liquid metal hinges to improve durability and help minimize screen creasing. Today, a Chinese leaker provided more details on the properties of this hinge material that help to clarify why Apple chose it for its first foldable device.
According...
The iOS 19 mockup images that leaker Jon Prosser shared today are not representative of the actual iOS 19 design, Bloomberg's Mark Gurman said on social media.
According to Gurman, the images that are "floating around" are based on "very old builds" or "vague descriptions," and are lacking key features. Gurman says that we can "expect more from Apple in June."
Gurman made the same comment ...
If you pay for iCloud storage on your iPhone, Apple has a new perk for you, at no additional cost.
The new perk is the ability to create invitations in the Apple Invites app for the iPhone, which launched in the App Store last month.
In the Apple Invites app, iCloud+ subscribers can create invitations for any occasion, such as birthday parties, graduations, baby showers, and more. Anyone ...