After the automatic upgrade from Windows 11 24H2 to 25H2 and the mandatory restart, the fingerprint login no longer worked. The registered fingerprints have disappeared, and new ones cannot be registered because Windows claims the sensor is not compatible.
 
I have also installed all optional driver updates, but that did not change anything.
 
See also https://superuser.com/q/1932686.

It appears that Microsoft changed the Enhanced Sign-in Security (ESS) validation mechanism starting with the Jan29 1D update (KB5074105).
 
If the OS build number is 26100.7705 or later (Windows 11 24H2) or 26200.7705 or later (Windows 11 25H2), and the SecureFingerprint registry key is not set, this issue occurs.
 
Since Lenovo preload images include this registry key by default, the issue does not occur when using a Lenovo preload image. Based on the reported cases, the affected users are likely using:
 
- a custom image created from scratch, or
- an image installed via Connected System Recovery (CSR).
 
Up to the previous builds, the fingerprint reader (FPR) was treated as ESS-capable even without the SecureFingerprint registry key, as long as the system had an ESS-capable camera and ESS was enabled.
 
However, starting with the newer builds, if the SecureFingerprint registry key is missing, the OS considers the fingerprint reader not ESS-capable. As a result, when ESS is enabled for the camera, fingerprint authentication no longer works.
 
We are still validating this behavior. However, if the information provided by Microsoft is accurate, this issue is expected to be resolved by the 3D update (scheduled for the 4th week of March).
 
 
Possible Solutions / Workarounds
 
(Option 1 is the most strongly recommended)
 
1. Set the SecureFingerprint registry key using n32gh06w.exe, available here: How to enable or disable Windows Hello Enhanced Sign-in – Windows 10 version 20H2 or later, and Windows 11 (Lenovo Support US)
2. Wait for the 3D update, which is expected to address this behavior.
3. Disable Enhanced Sign-in Security (ESS) via: Settings → Accounts → Sign-in options → Enhanced sign-in security (This option appears only after the 1D update or later is installed.)
4. Uninstall the recently installed KB and roll back the OS build to a version earlier than 7705.