Hi,
Actually I didn't have any warning in the web browsers. It's probably because I imported the CA certificates in the certificate stores already. It seems that the issue is with the SSL Server PSE since previously, I put the CA certificates there, restarted the ICM manually, cleared the browser cache and restarted the browser again but the issue still occur. Until later when I restarted the system, the errors are not seen in the log anymore.
Regards
Duy