iOS 8.0 has a serious flaw with iHealth services and the bug is so big that Apple decided to pull the update. We knew that a fix is on the way and last night US customers started receiving iOS 8.0.1. Many jumped to install this 73.1 MB update, but it did not help.
It turns out that this update tends to break the cellular service and Touch ID functionality. This translates to you cannot make calls or use Touch ID for added security including unlocking. Affected users who experience these problems have to reinstall iOS 8.0 via iTunes and the procedure is well documented at Apple’s support website.
The manual downgrade to 8.0 will break the iHealth services once again, but Apple promises that there should be an 8.0.2 update coming very soon. Apple had an excellent track record with its software updates and iPhone 6 and iPhone 6 Plus are definitely going through a rough patch. Despite selling more than 10 million new iPhones in the first week of sales, they continue to get some not so favourable coverage brought about broken software. It doesn’t help that the new iPhone 6 Plus bends in people's pockets, either.
The iPhone 6 and iPhone 6 Plus will get the iOS 8.0.2 in the next few days, so at least one of these issues will be addressed.