You cannot renew a certificate that has already expired. If you try to renew a certificate that has expired, the certification authority (CA) will reject the request, and you will see an error message similar to "Error Verifying Request Signature or Signing Certificate. A required certificate is not within its validity period when verifying against the current system clock or the timestamp in the signed file." This message will also be displayed in the Failed Requests node of the issuing CA. If your certificate has already expired, you must request a new certificate instead of renewing the existing certificate.