Q: Touch ID purchase on iOS 8.3

Read this: Use Touch ID on iPhone and iPad - Apple Support

Did your verify your credit card info in Settings > iTunes & App Store > Apple ID:?

I confirm this bug. Can't use anymore touch id to buy apps on ios 8.3. It worked like charm on previous releases 

See this thread with others having the same issue: looking like a widespread bug in iOS8.3 that wasnt there in the beta versions

Touch ID not working after 8.3 update for App Store purchases

SO unfortunately it looks a major bug

Yes having the same issue iOS 8.3 no touch ID for App Store or iTunes purchases. Can unlock with touch id

1. Launch Settings on your iPhone or iPad
2. Tap on Touch ID & Passcode
3. Enter your Passcode or Password
4. Toggle iTunes & App Store to OFF
5. Press the Home button to return to the Home screen.
6. Reboot your iPhone or iPad. (Here's how)
7. Enter your Passcode or Password at the Lock screen
8. Launch Settings on your iPhone or iPad
9. Tap on Touch ID & Passcode
10. Enter your Passcode or Password
11. Toggle iTunes & App Store to ON

My 6+ was doing that too, but I "fixed" it (so far)... This is what I did...

1) Settings > Touch iD & Password > iTunes & App Store > OFF

2) press & hold the lock button & home button until my phone reset

3) turned my phone back on

4) Settings > Touch iD & Password > iTunes & App Store > ON

5) when I did that, it said that I needed to enter my Apple ID password for it to work.

6) After I entered my password, my Touch ID works for the APP Store.

idk if it will keep working or not, but so far it is working.

I'm having the same problem with my iPhone 6+ w/iOS 8.3 (12F70) installed.

Actually, my Touch ID don't work at all. When I try to swipe the checkbox on, the iPhone returns me the following message:.

"FAILED. Unable to complete Touch ID setup. Please go back and try again."

I did it. Many times. Already tried the Lock+Home reboot and it's not working.

I'm really worried if there's a problem inside my iPhone or it's just a bug.

I really don't know what else I can do to solve this problem.

Copy from the Apple support doc link in my previous post :

If Touch ID doesn't recognize your finger, you'll be asked to try again. After three attempts, you'll be given the option to enter your passcode. After two more tries, you'll need to enter your passcode. In addition, you'll need to enter your passcode to unlock your iPhone or iPad in these cases:

• After restarting your device
• When more than 48 hours have elapsed from the last time you unlocked your device
• To enter the Touch ID & Passcode setting