Some models of Google’s new smartphone Pixel 4 are experiencing an error that ‘Face Unlock,’ a biometric function, doesn’t work, according to a foreign report.

Reportedly, some models of Pixel 4 reported error messages such as “Unable to check face. Try again” and “Unable to check face. Hardware not available.”

Some users have been having problems since installing security updates released by Google, and complained that even after deleting and re-registering the face unlock data, the error would still persist. In addition, some users report that even face unlock data can’t be deleted and the factory reset didn’t solve the problem.

Google first introduced Face Unlock in the Pixel 4 series. At the time of the announcement, Google introduced a radar detection feature called ‘Soli radar’ to enable “fastest and safest” facial unlocking.

However, in October last year, Pixel 4 released a security flaw that could be unlocked by face recognition even when the eyes were closed. Google says it’s investigating a “face unlock” error, but doesn’t know when the update will be released.