unable to active touch id in this ipad ( since last update :(

Begin with a forced-restart of your iPad - as this will often resolve an isolated software issue:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

If the problem remains unresolved, try setting-up TouchID with new fingerprints:

Use Touch ID on iPhone and iPad - Apple Support

If Touch ID isn't working on your iPhone or iPad - Apple Support

If you continue to experience difficulties, you might be best advised to seek assistance directly from from Apple Support - and request a remote diagnostic test. You can contact the Support Team using the Get Support link at top-right of this page. Alternatively, you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/gb/app/apple-support/id1130498044

You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad. If your iPad requires repair, you’ll be in the best possible place to explore your available options:

Genius Bar Reservation and Apple Support Options - Apple