Google Pixel 4 introduced an advanced facial recognition system that serves as the primary means of authenticating the phone.
Doing a factory reset seems to have worked out for some users, however, Face Unlock continued to show error for others even after a factory reset.
In some cases, the face unlock system stopped working after installing the January OTA update. For some users, a notification to re-register their face is appearing even with their face data already enrolled.
The list of folks with the issue started in November at Google's Pixel Phone Help forum and has only grown since.
On top of this, some users weren't able to even delete their face unlock data, and restarting the phone in safe mode - or completely factory restoring it - wasn't a guaranteed fix, either.
As per the reports, the users of the Pixel 4 device has got a message which says, "can't verify Face", and "Hardware not available".
The face unlock failure reported both while trying to unlock the phone or in apps.
While the Pixel 4 isn't alone - joining the likes of the recent iPhones in resorting exclusively to facial recognition for secure unlocking - these reports of the feature failing act as a warning against such reliance. However, the solution apparently does not work, it does not work for all users.
The error messages users getting on their Pixel 4 also vary depending on the stage they are in. Now, the system has run into another user-facing problem.
Google yet to acknowledge the issue officially and release a fix for it. However, the company is investigating the complaints of Pixel 4 users and could resolve it soon.