Several users have reported an issue in which iPad stops responding while the screen is locked and an alert popup says: “This iPad cannot back up to iCloud without a verified email address”.
Resolution
Reset your iPad. To reset your iPad, simply hold down on the sleep/wake (on/off) and home buttons simultaneously for about 10-15 seconds until the Apple Logo appears (ignore the red slider); your device will then reboot. This process will NOT erase any of your settings, data or apps.
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