Several troublesome issues have resurfaced with the iOS 9.1 release as users have been flooding Apple Support forums and other community sites with complaints regarding the inability to connect to the App Store or access native services such as Apple Music and Game Center. The same issues were first spotted in iOS 9.0.2, wherein affected users could simply try logging out and logging back in to the App Store to fix the problem.
iOS 9.1 was actually meant to fix all these issues. But, the situation has become worse with Apple ceasing to sign older firmware including iOS 9.0.2 as it is no longer possible to attempt the simple log-out and log-in fix to overcome the App Store issue.
As iPhone Hacks reports, several users are complaining that their Apple ID is no longer being recognised after a successful logout. Consequently, they are being denied access to Apple's native services such as Game Center and Apple Music.
In some other cases, users have tried rebooting their devices and resetting them to factory settings. But, nothing seems to fix this issue.
Some users have been lucky to be able to sign back into the App Store after several attempts. However, the Store reportedly fails to display their past purchases, updates to installed apps, or results in random freezes with the device.
Some users are able to use Game Center, but cannot access Apple Music or App Store for some reason. Others can access Apple Music, but not the App Store and Game Center.
Several iOS users have confirmed that the issues kicked off following the iOS 9.1 upgrade as they never faced such problems with iOS 9.0.2. Apple is yet to comment on the prevailing issues in iOS 9.1. However, you can always check out the latest updates with temporary workarounds and fixes being reported on the Apple Support Community page.