2231896 - Exception 'CX_SOAP_CORE' because of syntax error in transformation when calling Web Services for ABAP

A Web Service was called, either SAP as provider or consumer. PI might be involved in the scenario. The execution fails, even if the HTTP call was successful, because parsing the request or response results in an ST22 dump:

Error when calling SOAP Runtime functions:
This exception is closely related to a previous exception "CX_XMS_SYSERR_PROXY", which was raised in program "CL_PROXY_STYLESHEET_UTILS=====CP", in (include) program "CL_PROXY_STYLESHEET_UTILS=====CM003".
The reason for the exception occurring was: Error during proxy processing

The termination occurred in ABAP program "CL_WS_PROXY_RUNTIME_INBOUND===CP", in "IF_WS_PROXY_RUNTIME_INBOUND~SET_OPERATION_TAG". The main program was "SAPMSSY1".

System raises one or more of the following error messages:

• Transformation <ID_of_transformation> contains syntax error
• SRT: Generation of Proxy Adapter failed
• <ID_of_transformation> does not exist

• Web Services for ABAP
• SAP NetWeaver

CL_WS_PROXY_RUNTIME_INBOUND, CL_PROXY_STYLESHEET_UTILS, inactive transformation, RS_RETRIEVE_XSLT, transformation contains syntax error , KBA , transformation xx contains syntax error , rs_retrieve_xslt , BC-ESI-WS-ABA-RT , WebServices ABAP Runtime , BC-ESI-WS-ABA , Web Service and SOAP - ABAP , Problem