1. Manual intervention: after the face recognition fails, the system will automatically switch to manual verification or review, and the human operator will review the face recognition failure, decide whether to pass the signature according to the accuracy of its information, and judge according to some information. Even if face recognition fails, its information is accurate and it can still be signed.

2. Technical problems or errors: Face recognition technology is not completely accurate, and there are errors or faults. After the face recognition fails, it is a recognition error caused by ambient light, shooting angle, facial expression or other factors. The system did not completely eliminate some errors, and finally acquiesced in the success of the signature, which is the result of some defects or technical deficiencies in the design and algorithm of the system.