Fingerprint Not Working After Sleep?

If you're using fprintd for fingerprint authentication on Linux and encounter this error after waking your system:

Device reported an error during identify: Cannot run while suspended.

…it likely means the fingerprint device fails to recover correctly after suspend or hibernate.

The Quick Fix

You can fix this by restarting the fprintd service automatically after resume. Here's how:

1. Create a systemd service

Create a file at /etc/systemd/system/restart-fprintd-after-suspend.service:

[Unit]
Description=Restart fprintd after suspend
After=suspend.target hibernate.target hybrid-sleep.target suspend-then-hibernate.target

[Service]
Type=oneshot
ExecStart=/bin/systemctl restart fprintd.service

[Install]
WantedBy=suspend.target hibernate.target hybrid-sleep.target suspend-then-hibernate.target

2. Enable the service

Enable the service running this command:

sudo systemctl enable --now restart-fprintd-after-suspend.service

Now fprintd will restart automatically after suspend or hibernate, and your fingerprint sensor should work reliably again.