1. Signature key mismatch: Make sure that the signature key you use matches the key stored in the system. If the keys do not match, the signature check will fail.
2. The certificate has expired or is invalid: signature checking usually depends on a valid certificate. If the certificate is expired or invalid, the signature check will fail. Please check whether your certificate is valid and make sure that it has not expired.
3. Incompatible communication protocols: Different devices may use different communication protocols. If the communication protocols between devices are incompatible, the signature check may fail. Ensure that devices communicate using the same communication protocol.
4. Network connection problem: Unstable or interrupted network connection may lead to signature check failure. Please check the network connection and try to check the signature again.
5. Software or hardware failure: Software or hardware failure may cause signature check to fail. If possible, try to restart the device or reinstall relevant software for troubleshooting.