Enter the device settings section and then Touch ID settings, and if the above methods do not solve your problem, maybe resetting the settings of this feature will be useful.
In the touch ID and iPhone security code settings section, you will see various programs and options that are active. You must disable all these options. Before doing this, make sure all settings are disabled and then restart your iPhone. Now go back to the Touch ID settings and re-enable the options from the previous step.
Doing this will most of the time fix software errors that can prevent the fingerprint sensor from working properly. Now scan your finger again to see if the problem is fixed or not.
Remove fingerprints registered on iPhone
If you have registered your fingerprint on iPhone but it is not recognized correctly, maybe the problem is related to the movement of your finger or a software error, and in fact, the Touch ID system may not have registered a correct initial image of your fingerprint pattern. In any case, erasing the previous fingerprints and registering them again will probably fix the problem.
Go to iPhone settings and select the Touch ID settings section. Scroll down and touch the Delete Fingerprint box to delete the fingerprint. If you have registered multiple fingerprints, it is better to delete them all so that the original fingerprint images are completely reset.
Restart your device and then register your fingerprint carefully. Make sure you keep your finger firmly on Touch ID while registering. Note that the initial scanning process takes a little time and you have to keep your finger on the sensor for a long time.
Clear network settings on iPhone
Clearing network settings will clear all saved passwords for connecting to Wi-Fi networks, as well as the list of Bluetooth devices paired with the phone. Although this solution may seem a little strange to solve the problem of the fingerprint sensor not working on the iPhone, but reports have shown that some people have succeeded in solving the problem by doing it.