HTTP 400 error encountered during Symantec VIP Cloud transactions.
This issue typically happens during 2-Way TLS communication when the VIP auth certificate sent by the client is expired, revoked, or invalid. During the TLS communication, both client and server exchange their public certificates to accomplish the handshake. The client validates the server certificate and the server validates the client certificate. During the TLS handshake, if the VIP client auth certificate is not valid, the VIP server will send a 400 - Bad request "SSL certificate error".
Follow these steps from the VIP Manager HELP to request and download the VIP certificate.
(Note: Proxied VIP traffic should be made persistent)