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
Apple is planning to announce several new features for the Messages and Phone apps on iOS 26, according to Bloomberg's Mark Gurman.
In a lengthy report outlining his WWDC 2025 expectations today, Gurman said that the two main changes in the Messages app will be the ability to create polls, as well as the option to set a background image within a conversation.
9to5Mac was first to report...
While the so-called "iPhone 17 Air" is not expected to launch until September, there are already plenty of rumors about the ultra-thin device.
Overall, the iPhone 17 Air sounds like a mixed bag. While the device is expected to have an impressively thin and light design, rumors indicate it will have some compromises compared to iPhone 17 Pro models, including worse battery life, only a single ...
While the spotlight has been on CarPlay Ultra lately, the regular version of CarPlay is set to receive some enhancements alongside iOS 26.
Apple will announce iOS 26 at WWDC 2025 next week, and the software update is expected to upgrade the CarPlay experience in at least two ways.
The first iOS 26 beta should be seeded to developers shortly after Apple's keynote, and the update will...
The Apple Watch provides highly accurate measurements of heart rate and step count, but their estimates of calories burned can be significantly off, according to a new peer-reviewed meta-analysis conducted by researchers at the University of Mississippi (via CNET).
The study reviewed 56 previously published studies evaluating the Apple Watch's performance against gold-standard clinical tools ...
If the Mail app on your iPhone is not working lately, you are not alone.
A growing number of iPhone users are seeing a blank screen in the Mail app, according to comments posted across the MacRumors Forums, Reddit, Apple Support Community, and other online discussion platforms. Affected users are unable to view any emails in their inboxes, and the app can also become glitchy and...
In a lengthy report outlining his WWDC 2025 expectations today, Bloomberg's Mark Gurman shared more details about iOS 26's rumored new design.
According to Gurman, iOS 26 will feature a "digital glass" design inspired by visionOS, the operating system for Apple's Vision Pro headset. That is a well-known rumor by now, but he goes on to provide some more specific details, as listed below:There ...
macOS 26 will drop support for several older Intel-based Mac models currently compatible with macOS Sequoia, according to a private account on X with a proven track record of leaking information about Apple's software platforms.
macOS 26 will be compatible with the following Mac models, the account said:MacBook Air (M1 and later)
MacBook Pro (2019 and later)
iMac (2020 and later)
Mac...
