Apple has blamed a rogue App Store server for making more than 100 apps unusable, including Angry Birds Space, after iPhone and iPad users updated them.
According to Apple, the server wrongly included a digital rights management (DRM) code, which made it impossible to open them. But the company said the problem had been fixed.
Apple normally uses DRM to ensure that apps work only for users who have paid for them or are authorised to use them, according to the Telegraph.
The problem was discovered by Marco Arment, who developed Instapaper, an app for aggregating and displaying online articles.
He compiled a list of more than 100 other apps affected by the server problem, including Angry Birds Space, Word Lens and Yahoo! Search.
Arment led calls on Apple by app developers to acknowledge and fix the problem as soon as possible.
Apple said if any newly downloaded apps had been affected, users should download them again from the App Store.