iOS: Your passcode is required to enable Touch ID

Question

Occasionally, when unlocking my iPhone or iPad, I get the following message:

Your passcode is required to enable Touch ID

Now this is not after a number of failed attempts or turning the device off. The device was used within the last 12 hours. Two of the devices are less than 2 months old, and one is a year old. Everything is up to date. It appears to be happening more-or-less at random.

Does anybody know why this message might appear?

Answer 1

There are certain rules that iOS uses that govern when your iPhone will prompt you for your passcode, and one of these relates to an 8hr period during which Touch ID has not been used. That alone would explain the scenario in your question (i.e. some nights you’re getting 8+ hrs of sleep, and other nights you’re not).

All of the Touch ID rules can be found in Apple’s iOS Security Guide. In summary though, the rules governing when a passcode is required instead of your fingerprint, are as follows:

• The passcode has not been used to unlock the device in the last six days
• Your fingerprint has not been used to unlock the device in the last eight hours ¹
• You have just powered up (or rebooted) your device
• Your device has not been unlocked for more than 48 hours
• You’ve unsuccessfully tried to use your fingerprint on five consecutive attempts
• Whenever you add a fingerprint to your Touch ID settings
• Your device has received a remote lock command

Regarding that last point, this refers to iCloud’s Lost Mode function. For more info you can read iCloud: Use Lost Mode.

See more details: http://www.macworld.com/article/3072181/ios/new-touch-id-rules-why-you-have-to-enter-your-passcode-when-you-wake-up.html

¹ This is most likely the cause in your situation most of the time.

Answer 2

FWIW, I experienced the same thing on an iPad mini 4 on 9.2.1 today. Was using the iPad < 12 hrs before. The wording was identical to above. When I restart the device different wording is used: iPad requires your passcode after restarting.

This implies something happening with Touch ID itself, rather than a date/time bug or the device restarting. Perhaps Touch ID or a related service is crashing unseen.

Answer 3

Maybe you have been accidentally touching the Touch ID sensor without realizing it and it locked up. This has happened to me before without a restart and apparently it had been trying to get my fingerprint in my pocket... Also, perhaps another culprit (maybe a child or loved one) has been messing with Touch ID.

Answer 4

This is a software bug in iOS 9. It happens to me at least twice a week on my iPad. You could submit a bug report to Apple, but I would imagine it will be fixed with either iOS 9.3 next month or iOS 10 in September.

Answer 5

Are we talking of phones that are in your (jeans) pocket? It happens to me if I accidentally hit the touch ID sensor when reaching into my pocket. The other culprit in my case is my daughter playing with my phone when I don't watch.