iPad When & why -- enter passcode vs. fingerprint ID to unlock?

[kirkbross]

My iPad usually accepts my thumb print to unlock, but sometimes it makes me enter my ID.

I want to understand the logic it is using to decide when one or the other is required.

After a reboot? Passcode makes sense.
Randomly asking for passcode after I've been using fingerprint ID for days? I want to know why.

 

[cmaier]

My iPad usually accepts my thumb print to unlock, but sometimes it makes me enter my ID.

I want to understand the logic it is using to decide when one or the other is required.

After a reboot? Passcode makes sense.
Randomly asking for passcode after I've been using fingerprint ID for days? I want to know why.

It will make you use your passcode again if Touch ID has failed multiple times or if it has been too long since the last time you entered a passcode. More specifically, if the passcode has not been used to unlock the device in the last 6 days, AND if touchID has not been used in 8 hours, then it disables touch id as a security precaution. (The exact times may have changed since these rules were uncovered).

 

[C DM]

My iPad usually accepts my thumb print to unlock, but sometimes it makes me enter my ID.

I want to understand the logic it is using to decide when one or the other is required.

After a reboot? Passcode makes sense.
Randomly asking for passcode after I've been using fingerprint ID for days? I want to know why.

Set a passcode on iPad

For better security, set a passcode that needs to be entered to turn on or wake up iPad.

support.apple.com

After you set a passcode, on supported models you can use Face ID or Touch ID to unlock iPad. For additional security, however, you must always enter your passcode to unlock your iPad under the following conditions:

- You turn on or restart your iPad.

- You haven’t unlocked your iPad for more than 48 hours.

- You haven’t unlocked your iPad with the passcode in the last 6.5 days, and you haven’t unlocked it with Face ID or Touch ID in the last 4 hours.

- Your iPad receives a remote lock command.

- There are five unsuccessful attempts to unlock your iPad with Face ID or Touch ID.

 

[kirkbross]

Thank you both. Precisely the info I was looking for.