Arch Linux

mr.error

Member

From: Iraq

Registered: 2025-08-08

Posts: 1

Validity VFS7500 Fingerprint Sensor - Enrollment Fails protocol error

Hello everyone,

I’m having trouble getting my Validity Sensors VFS7500 fingerprint sensor working on Arch Linux. The device works fine on Windows, so the hardware is functional, but on Linux, I keep getting a USB protocol error that prevents enrollment.

Hardware info
Device: Validity Sensors VFS7500 Touch Fingerprint Sensor

USB ID: 138a:0090

Works perfectly on Windows

System info
Arch Linux, latest rolling release

Kernel: 6.15.9-arch1-1

libfprint version last version

validity-sensors-tools version: last version

fprintd version:  last version

Problem description
When running:

*fprintd-enroll -f right-index-finger $USER*
I get:
Using device /net/reactivated/Fprint/Device/0
failed to claim device: GDBus.Error:net.reactivated.Fprint.Error.Internal: Open failed with error: The driver encountered a protocol error with the device.

The device is detected correctly by lsusb:
Bus 001 Device 003: ID 138a:0090 Validity Sensors, Inc. VFS7500 Touch Fingerprint Sensor

Troubleshooting steps tried
Verified device detection with lsusb and kernel logs

Checked USB autosuspend and power management settings

Tested with both latest and LTS kernels

Stopped and restarted fprintd service multiple times

Tried enrollment with fprintd-enroll and validity-sensors-tools

Confirmed kernel config has USB HID enabled (CONFIG_USB_HID=y)

Ensured relevant kernel modules (usbhid, usbcore) are loaded

Ran validity-sensors-tools -t led-dance which failed with an assertion error (Exception: Failed: 04af)

Examined kernel logs showing repeated USB device resets (usb 1-9: reset full-speed USB device)

Collected debug logs using G_MESSAGES_DEBUG=fprintd,fprintd-debug

Relevant logs excerpts
dmesg:
usb 1-9: reset full-speed USB device number 3 using xhci_hcd
usb 1-9: reset full-speed USB device number 3 using xhci_hcd

fprintd-enroll:
Using device /net/reactivated/Fprint/Device/0
failed to claim device: GDBus.Error:net.reactivated.Fprint.Error.Internal: Open failed with error: The driver encountered a protocol error with the device.

validity-sensors-tools:
Exception: Failed: 04af

Additional details
USB HID support is enabled in kernel

No conflicting drivers loaded for the fingerprint device

Device shows up correctly on D-Bus as /net/reactivated/Fprint/Device/0

No other fingerprint readers connected

Request
Has anyone experienced this or can offer any pointers to fix this? Any help on diagnosing the USB protocol error or workarounds to make the Validity VFS7500 work with libfprint/fprintd on Arch Linux would be greatly appreciated.

Thanks a lot in advance!

System info commands output (if needed)
uname -a
lsusb -v -d 138a:0090
pacman -Qi libfprint validity-sensors-tools fprintd
journalctl -k | grep usb

If you want me to help add more info or logs, just ask!

Blauhirn

Member

Registered: 2018-05-21

Posts: 7

Re: Validity VFS7500 Fingerprint Sensor - Enrollment Fails protocol error

According to https://blog.getreu.net/20210906-VFS750 … -Debian-11, for VFS7500, you need https://github.com/3v1n0/libfprint-tod-vfs0090. And indeed, if you install https://aur.archlinux.org/packages/libf … fs009x-git which installs https://gitlab.archlinux.org/gugah/libfprint (different? same? I have no idea), this will replace fprint with a custom version that actually works - at least on my 460s.