This prompt is usually caused by abnormal hardware connection of U shield, abnormal driver of U shield or no wrong certificate selected when the page prompts "Please choose my certificate to sign".

The preliminary solution is that the certificate can be recognized when inserting the network silver shield, but the signature fails in the business operation, so it can be determined that the problem lies in the certificate. Check the expiration time of the certificate and find that it has not expired. Uninstall the certificate and reinstall it.