After checking a MPL Log in SAP Cloud Platform Integration the error message shows the following:

"Inbound processing in endpoint at /receiveIDOC failed with message"Fault:[com.ctc.wstx.exc.WstxLazyException] Illegal character entity: expansion character (code 0x2
at [row,col {unknown-source}]: [########]", caused by "WstxParsingException:Illegal character entity: expansion character (code 0x2
at [row,col {unknown-source}]: [########]"

The payload contains illegal characters that are rejected in the inbound adapter level in SAP Cloud Platform Integration.

Perform checks at the sender SAP ERP system before the data is sent to the SAP Cloud Platform Integration tenant endpoint and look for certain characters such as # , < , > , & , " , '. These characters need to be escaped in the XML because they are used by XML itself.

If any of these special or illegal characters are present in the inbound IDOC payload, those have to be removed from the IDOC, and then the IDOC has to be reprocessed manually in SAP ERP using the transaction code WE19.

To extract the IDOC XML, use the ABAP program RCOD_DOWNLOAD_IDOC_AS_XML by providing the IDOC number.

SAP Integration Suite Managed Gateway > Managed Gateway for Sourcing Integration
SAP Integration Suite Managed Gateway > Managed Gateway Foundation & Tools > Managed Gateway for Managed Gateway Portal