Apple Inc
Apple said it would release iOS 8.0.2 in the next few days to fix the issue. In the meantime, it offered step-by-step instructions to reinstall iOS 8 using iTunes.
The company said users should make sure that they are using the latest version of iTunes before reinstalling iOS 8.
Apple said its health app would not work in iOS 8 after these steps, but would be fixed in iOS 8.0.2.
The company pulled the iOS 8 system after users took to microblogging site Twitter to post their complaints.