AllThingsD is reporting that updating school iPads to iOS 7 failed to restore the supervision profiles, meaning that all of the protective filters put in place were lost.
From posts on the Apple Support Communities, the problem appears to be widespread. Some schools, whose iPads are still on iOS 6, are editing the school network DNS files to block access to the update server, preventing devices from downloading the update.
Apple says it is aware of the issue and is working on a fix.
Apple has so far issued two updates to iOS 7, with iOS 7.0.3 expected to be released shortly.
Last month, the LA School District decided to place a temporary halt on its plans to make iPads available to all of its 640,000 students after kids learned how to bypass the restrictions.