IO exception when request sent from soap connector

I’m send request from soap connect I’m getting status code as 500 and getting xml response as

<?xml version="1.0" encoding="UTF-8"?>

env:Header/
env:Body
env:Fault
env:Client
Unable to parse the incoming request

<java:string xmlns:java=“java.io”>java.io.IOException: Null content type
</java:string>

</env:Fault>
</env:Body>
</env:Envelope>