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 plans to announce new products "this week," according to Bloomberg's Mark Gurman.
Apple's "Mac Your Calendars" teaser last October
In his Power On newsletter today, Gurman said the products set to be updated this week include the iPad Pro, Vision Pro, and "likely" the base 14-inch MacBook Pro, with all three likely to receive a spec bump with Apple's next-generation M5 chip.
Gurman...
Apple's software engineers are internally testing iOS 26.0.2, according to MacRumors logs, which have been a reliable indicator of upcoming iOS versions.
iOS 26.0.2 will likely be a minor update that addresses bugs and/or security vulnerabilities, but we do not know any specific details yet.
The update will likely be released within the next few weeks.
Last month, Apple released iOS...
Buried in its announcement about "F1: The Movie" making its streaming debut on December 12, Apple has also announced that Apple TV+ is being rebranded as simply Apple TV.
A single line near the end of the press release states "Apple TV+ is now simply Apple TV, with a vibrant new identity," though Apple's website has yet to be updated with any changes, so we're unsure on the details of the...
While the iPhone 18 Pro and iPhone 18 Pro Max are still nearly a year away, a handful of new features and changes have already been rumored for the devices.
Below, we have recapped some of the early iPhone 18 Pro rumors so far.
Smaller Dynamic Island
The standard iPhone 18, iPhone 18 Pro, and iPhone 18 Pro Max will be equipped with a slightly smaller Dynamic Island, but the devices will...
After releasing AirPods Pro 3 last month, Apple is already working on the next AirPods Pro, according to Bloomberg's Mark Gurman.
It is unclear if the new AirPods Pro would be branded as AirPods Pro 4, or if they would be considered an updated version of AirPods Pro 3. Gurman did not take a position, opting to describe them as a "new version" of the "high-end in-ear buds."
AirPods Pro 2...
Apple marketing chief Greg Joswiak today teased the launch of an upcoming product, saying "something powerful is coming" on social media.
Subscribe to the MacRumors YouTube channel for more videos.
A short animation accompanying Joswiak's teaser reveals a brief glimpse of a MacBook Pro along with the words "coming soon." The shape of the MacBook Pro is a V, which is the Roman numeral...
Apple today updated the 14-inch MacBook Pro base model with its new M5 chip, which is also available in updated iPad Pro and Vision Pro models.
In addition, the base 14-inch MacBook Pro can now be configured with up to 4TB of storage on Apple's online store, whereas the previous model maxed out at 2TB. However, the maximum amount of unified RAM available for this model remains 32GB.
Like...
Apple's second-generation smart glasses with an in-lens display may have two modes, depending on which device they are connected to.
Meta Ray-Bans without an in-lens display
In his Power On newsletter today, Bloomberg's Mark Gurman said he was told a future version of Apple's smart glasses may be able to run a full version of the visionOS operating system when they are paired with a Mac, and...
Apple today announced the next-generation iPad Pro, featuring the custom-designed M5, C1X, and N1 chips.
The M5 chip has up to a 10-core CPU, with four performance cores and six efficiency cores. It features a next-generation GPU with Neural Accelerator in each core, allowing the new iPad Pro to deliver up to 3.5x the AI performance than the previous model, and a third-generation ray-tracing ...