I wanna know do immigration officers asking for biometrics at frankfurt airport (Germany).
If you are worried about fingerprint not reading correctly, its shouldn't be an issue. If its not read properly, it will be reattempted after cleaning your hand. If still not working, usually, they will match up with the rest of the details like your photo and all.
You won't be denied entry just because your fingerprint is not reading properly.
Automated gates (which in Frankfurt are only open to EU and Swiss citizens and, with prior enrollment, to citizens of a handful of other countries) do rely on biometric data, namely the picture of your face that's recorded in your passport.
Fingerprints are not scanned as a matter of course when entering the Schengen area. There is also no requirement to do so and no process to record or store them.
If you have a short-stay visa, your picture and fingerprints have been added to the Visa Information System (VIS) when you applied. Other law enforcement databases, including the Schengen Information System (SIS) also include biometric data. So if there are doubts whether the passport and visa you present are really yours or any reason to suspect that there could be an alert about you, border guards can use these databases to further ascertain your identity.