Sales Order Update to 3PL using External Middleware

Summary:

The sales orders created in Oracle Fusion are shipped through Third Party Logistics system (3PL). The integration from Fusion to 3PL system is not through Oracle OIC but a different middleware. The 3PL shipment integration is working successfully, however the Sales Order update integration is failing with below error while updating the SO. The External Web Services of middleware are already configured. They are successfully called through SOAP UI but not triggered when SO is updated. Any suggestions for resolving this would be helpful. Thank You.

Version (include the version you are using, if applicable): 26C