SAP Knowledge Base Article - Public

3057179 - Error "SoapFault:faultstring=MustUnderstand headers" in CPI during C4C account replication to Marketing Cloud


When replicating accounts from SAP Cloud for Customer to SAP Marketing Cloud, you see the following error in the SAP Cloud Platform Integration message monitoring:

Inbound processing in endpoint at /C4C/yMKT/BusinessPartnerReplicationSelfInitiatedOut failed with message "SoapFault:faultstring=MustUnderstand headers: [{}Action, {}To] are not understood.; faultcode={}MustUnderstand"


SAP Cloud for Customer

SAP Cloud Platform Integration


The C4C Communication System is not configured as expected.


  1. Log on to SAP Cloud for Customer. 
  2. Go to the Administrator Work Center.
  3. Navigate to General Settings work center view.
  4. Open Communication Systems under Integration division.
  5. Open the communication system which is created for C4C-Marketing integration.
  6. Set the "Preferred Application Protocol" to "5 - Web Service".


soap:MustUnderstand C4C MKT INTEGRATION , KBA , LOD-CRM-INT-YMT , Integration of C4C with Marketing , How To


SAP Cloud for Customer core applications 2102