This happens every few days: I wake up in the morning, try to unlock my phone with Touch ID, and it prompts me for my password. The length and complexity of my password and my drowsiness in the morning make for an unpleasant combination. Why does this keep happening?

Detailed information:

  • I am using an iPhone 6 (64 GB), running iOS 9.3.2, though this has been an issue for several versions now (at least as far back as 9.3.0).
  • It happens regardless of whether or not I charge my phone at night.
  • It is not caused by iOS updates, because I always manually update iOS.
  • It sometimes happens in the daytime, but seems to be more common after not using my phone for 6+ hours (due to being asleep).
  • I have my "Require Passcode" setting set to "Immediately".
  • I am using a custom alphanumeric code, not a custom numeric code or a 4-digit numeric code.
  • I have Touch ID enabled. Other than when this issue rears its ugly head, it works perfectly.
  • Generally they'll ask you for the password if a) your phone has rebooted b) your TouchID fails to recognise your fingerprint
    – Quill
    Jul 13, 2016 at 1:01
  • @Quill Neither of those are the case. My SIM card is password-protected, and thus requires a separate password to be entered upon reboot. That password prompt doesn't appear, so my phone didn't reboot. Being required to enter the passcode only happens after numerous successive failures to recognize the fingerprint, and comes with a different message on the screen. Since my phone stays locked all night and prompts me for my password before I attempt to use Touch ID, and doesn't show the "fingerprint reading failed" message, that isn't the case, either.
    – user191889
    Jul 13, 2016 at 1:06
  • So does it just go to the keypad screen or does it say the "Enter your passcode to enable Touch ID" thing?
    – Downgoat
    Jul 13, 2016 at 1:12
  • @Downgoat It says "Enter your passcode to enable Touch ID" - as if it had rebooted.
    – user191889
    Jul 13, 2016 at 1:13
  • @Downgoat I searched before posting, but I apparently missed that question. I agree that this is a duplicate, though this one has a lot more information.
    – user191889
    Jul 13, 2016 at 1:15