We have had an interface between SFDC and our company for well over a year. All of a sudden, updates to SFDC are erroring out with:
Environment: %Environment%
Server: %Server%
Transaction Type: %TransactionType%
Error Message: [ISS.0088.9139] Output parameters do not conform to targetOutputSignature:
                errorCode=VV-002
                pathName=/fault/detail/fns:UnexpectedErrorFault/fns:upgradeURL
                errorMessage=[ISC.0082.9026] Undefined Object found
 
                errorCode=VV-002
                pathName=/fault/detail/fns:UnexpectedErrorFault/fns:upgradeMessage
                errorMessage=[ISC.0082.9026] Undefined Object found

No known chages to the environment. Login by the interface user is successful.