I am making an apex SOAP callout to an external system. THe connection worked fine last week but suddenly it is failing now due and it gives me this error:
Apex callout Web service callout failed: Unexpected element. Parser was expecting element 'http://schemas.xmlsoap.org/soap/envelope/:Envelope' but found ':h4'
When I tested the webservice throught SOAP UI it works fine and gives me the response. The external system and I are wondering what change has happended and why this error has popped out from no where. Any insights of what I should check when this error comes up?