1. Check whether the certificate has expired or been revoked. If so, you need to reapply or renew the certificate.

2. Confirm whether the system time is correct. If not, you need to adjust the time.

3. Add the certification authority to the list of trusted root certificates.

4. Check whether the certificate file is complete or damaged. If so, you need to download or regenerate the certificate again.

5. Check whether the signature algorithm is supported. If not, you need to upgrade the software version or change the signature algorithm.

In addition, there are some other situations that may cause the digital certificate signature display program to be abnormal, such as incorrect certificate format and incomplete certificate chain. Therefore, in the process of solving problems, it is necessary to comprehensively consider various possibilities and take corresponding measures. At the same time, in order to avoid the abnormality of digital certificate signature display program, we should pay attention to protect our digital certificate and avoid leakage or tampering.