I have integration scenario for sending PO/PO change/Proact from R/3 to SNC, everything was working till yesterday morning and suddenly all messages are failing in SAP PI with below error. We have not done any changes. The strange thing is this is failing in dev as well as in QA.
HTTP Status Code 200 Received But Error During Response Parsing: No XI Response Received XML element Envelope missing in SOAP message header (SAP XI Extension)
I can see some messages in sxmb_moni (we have not configured this) from sender component "Integration_Server_SID" and it's failed with below message
Proxy calls are not permitted on sender or
receiver side on the IS (client)