3723708 - Peer certificate rejected error during connection to Salesforce in PI/PO

• In Process Integration (PI) or Process Orchestration (PO), a previously working integration stops working suddenly with error "Peer certificate rejected by ChainVerifier"
• In this case, the interface is used for obtaining OAuth session IDs from the Salesforce application with hostname login.salesforce.com.
• The REST Receiver Adapter is involved. 
• Messages triggered from the ECC fail in the middleware PO production system.
• Error message: "SOAP: Error occurred: com.sap.engine.interfaces.messaging.api.exception.MessagingException: java.io.IOException: Failed to get the input stream from socket: iaik.security.ssl.SSLCertificateException: Peer certificate rejected by ChainVerifier".
• No recent changes have been made on the PI/PO side. 

• SAP NetWeaver 7.5

peer certificate rejected, ssl certificate exception, soap error, message processing failure, sap netweaver, process orchestration, middleware error, session id interface, certificate update, trust store, handshake issue, ECC production system, PO production system, renew, renewal, expiry, validity , KBA , BC-XI-CON-AFW-SEC , Security , BC-XI-CON-RST , Rest Adapter , Problem