I am using web service consumer in Mule4 and after configuration and deployed the application and triggered the target ARIBA SOAP service in logs I see below error:
org.apache.cxf.binding.soap.SoapFault: Error reading XMLStreamReader: Undeclared namespace prefix "soapenv" at [row,col {unknown-source}]: [1,14]
When I explored the error I see it is an issue at target system end :], please let me know whether it is end system thrown error or any pointers on what would cause this issue.
Link to Oracle documentation about Ariba Adapter (Cloud > Cloud Platform > Integration Generation 2 > Using the SAP Ariba Adapter with Oracle Integration Generation 2 > 5 Troubleshoot the SAP Ariba Adapter > Invalid SOAP Message Response Error)
The link you shared seems pretty clear. It is an issue on SAP Ariba side. The solution is also shared in the same page:
For some reason Ariba doesn't seem to be declaring the SOAP XML namespaces in its responses.
You have to follow the instructions to configure Ariba to include the namespaces in responses.