Purchase Order (PO) sent from Ariba Buying & Invoicing (P2P) is failing in Cloud Integration Gateway (CIG) with the following error:

org.apache.cxf.binding.soap.SoapFault: Error reading XMLStreamReader: Unexpected character 'j' (code 106) in prolog; expected '<' at [row,col {unknown

1. Check if the certificates are expired on ERP or S/4 HANA. If so, once the certificate is renewed POs will start to flow.
2. Do a test in CIG Connectivity Tool to test the connectivity between CIG and S/4 HANA or ERP and if it fails one of the possible issues is with Cloud Connector. To correct this, refer to CIG Installation Guide to review the Cloud Connector configuration: Configuring SAP Cloud Connector 

1. Expired certificate on ERP or S/4 HANA side.
2. Configuration issues in Cloud Connector.

Note: each issue is numbered according to the resolution and the cause of the issue (e.g.: issue 1 relates to cause 1 and can be resolved by following resolution 1).

For more information on the topics mentioned in this note refer to How to maintain certificates and Troubleshooting CIG Connection issues Guided Answers 

SAP Integration Suite Managed Gateway > Managed Gateway for Procurement