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ORA-29024: Certificate validation failure
*Cause: The certificate sent by the other side could not be validated. This may occur if
the certificate has expired, has been revoked, or is invalid for another reason.
*Action: Check the certificate to determine whether it is valid. Obtain a new certificate,
alert the sender that the certificate has failed, or resend.
John gave you the answer in OTN, as he said, problem and solution are external to Oracle, what do you expect in another Oracle forum?