A security bug on Mac computers is forcing some Apple users to delete and reinstall software they've downloaded from the App Store. First spotted by developer Paul Haddad, the problem seems to be caused by an expired security certificate used by Apple to verify apps. The iPhone-maker has since issued a new certificate (with an expiry date of April 2035, according to The Guardian), but this hasn't completely fixed the problem.

It's not clear which apps the bug is affecting, with some users reporting issues with multiple pieces of software, and others, only a single app. Similarly, while some people have fixed the problem by simply disconnecting and reconnecting to the Mac App Store, others say the only reliable solution is to reinstall all of the affected apps. In some cases, a reboot also seems to do the trick.

Well that would explain the MAS problem. pic.twitter.com/Nuqj9Uxxiz — Paul Haddad (@tapbot_paul) November 12, 2015

Uh, Apple, why are a bunch of my Mac App Store apps suddenly "damaged"?! pic.twitter.com/Afby6j5VtS — Graham (@greyham) November 12, 2015

Update, November 16th, 03.14AM ET: Apple has confirmed that the problems were caused by an expiring security certificate, but it seems that the app developers themselves were partly at fault. The company was trying to update the Mac App Store's security certificate from an older SHA-1 standard, to the newer, more secure, SHA-2, but this was not supported by some apps, leading to the need to reinstall certain pieces of software.