I am testing an integration between Salesforce and another system via Web Service Collouts. For that, I am using WSDL->APEX generated class. When invoke the web service via anonymous apex, I get a vague exception:
System.CalloutException: Web service callout failed: Failed to deserialize value '', due to:For input string: ""
I can't really wrap my head around it. The other system is a black box I do not have an access to, so I cannot look at the matter from the other side. Is anybody familiar with the exception? What is the likely cause?