So iOS 8.0.1 was filled with bugs that broke Touch ID and cellular data for many iOS users on the iPhone 6 and iPhone 6 Plus. But Don’t fret, if you’re in this precarious situation, we have an easy fix for you: Downgrade to iOS 8.0.
Well, actually, it’s sort of an upgrade in a weird and ironic way. Check inside for the full step-by-step tutorial. After you’re finished, your iPhone should work like normal.
Step 2: Turn off Find My iPhone on your device if you have it enabled. Go to Settings → iCloud, and disable the Find My iPhone switch.
Step 3: Connect your device to a Mac with iTunes installed.
Step 4: Open the device page on iTunes, and hold the Option key (Shift for Windows users) while clicking the Check For Update button. Find the IPSW firmware file that you downloaded in Step 1, select it, and click Open.
Step 5: A pop-up box will tell you that iTunes will update your iPhone to iOS 8.0 and will verify the update with Apple, click the Update button. Wait until your device updates, and enjoy your iOS 8.0 installation, with working Touch ID and cellular data!
The great thing about this method is that you don’t lose any of your phone’s settings or data. All of your pictures, messages, email, etc. should be ready and waiting on your when you downgrade.
Apple will probably issue an iOS 8.0.2 update in record time, but until then, this will likely be the best solution for those of you who need access to cellular data and Touch ID now.