Ubuntu 26.04 (Resolute) incompatibility: RegisterDevice method missing in open-fprintd

[sudo-ritvik]

Device: Lenovo ThinkPad T470s
Sensor: Validity Sensors 138a:0097
OS: Ubuntu 26.04 (Resolute)
python-validity version: 0.15 (installed from source)
fprintd / open-fprintd: open-fprintd 0.7~ppa2 (default on 26.04)

Issue:

On Ubuntu 26.04, python3-validity fails to register the device with open-fprintd due to an API incompatibility. The dbus-service calls mgr.RegisterDevice(svc) on startup, but the new open-fprintd Manager interface no longer exposes a RegisterDevice method — only GetDevices and GetDefaultDevice.

This results in the following traceback on every start:

dbus.exceptions.DBusException: org.freedesktop.DBus.Error.UnknownMethod: No such method RegisterDevice

As a result, fprintd-enroll returns No devices available and fingerprint authentication is completely non-functional on 26.04.

Notes:

• The firmware loads correctly via validity-sensors-firmware
• The python3-validity service starts but immediately fails when trying to register
• The uunicorn/open-fprintd PPA does not yet have a build for Ubuntu 26.04 (Resolute), so there is no installable package from the PPA either
• Workaround of using standard fprintd instead of open-fprintd is blocked because 26.04 repos only ship fprintd 1.94.5 which conflicts with open-fprintd

Request:

Could python-validity be updated to support the new open-fprintd Manager API, and/or could the PPA be built for Ubuntu 26.04? This sensor is not supported by mainline libfprint so python-validity is the only viable driver for ThinkPad T470s users on 26.04.

Happy to test any patches or provide additional debug output.