Error:The reason for the SOAP fault is: "Exception during creation of SOAP envelope structure"

Hi Team,

We doing performance test on couple of webservice-payloads , for one of the add document service we are facing "Error:The reason for the SOAP fault is: "Exception during creation of SOAP envelope structure"Error:SOAP request "SOAP Request" execution failed  in performance center when we added morethan 1 user per group. 

- Script is working fine for multiple iterations in VuGen i.e. add document success, same behavior with 1user load in performane center(PC) also.

- whenever we add multiple users load in PC, 1st user add document transactions are success & for remaining users getting above mentioned error. 

- we are attaching 1MB/2MB text files in soap_request, 

        ATTACHMENTS_FORMAT_MIME,
        ATTACHMENT_ADD,"FileName=1MB.txt", (first provided file path & later file attached to script itself both cases errors for multiple users load in pc)
        "ContentType=xml/text", "Id=123", 

>> it looks like only 2bytes request is sending for remaining users as part of request, any inputs on this will be really helpful.  is it script/tool issue?  any work arounds?

Action.c(44): SOAPAction: "http://URL"\r\n
Action.c(44): User-Agent: Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.1; Trident/6.0)\r\n
Action.c(44): Accept-Encoding: gzip, deflate\r\n
Action.c(44): Accept: */*\r\n
Action.c(44): Connection: Keep-Alive\r\n
Action.c(44): Host: <host>\r\n
Action.c(44): Content-Length: 2\r\n
Action.c(44): \r\n
Action.c(44): t=9874ms: 2-byte request body for "http://URL" (RelFrameId=1, Internal ID=2)
Action.c(44): \r\n
Action.c(44): t=9876ms: 181-byte response headers for "http://URL" (RelFrameId=1, Internal ID=2)
Action.c(44): HTTP/1.1 500 Internal Server Error\r\n
Action.c(44): Server: Apache-Coyote/1.1\r\n
Action.c(44): Content-Type: text/xml;charset=utf-8\r\n
Action.c(44): Content-Length: 1207\r\n
Action.c(44): Date: Wed, 26 Oct 2016 01:02:20 GMT\r\n
Action.c(44): Connection: close\r\n
Action.c(44): \r\n

<?xml version="1.0" encoding="utf-8"?><soapenv:Envelope xmlns:soapenv="http://schemas.xmls
Action.c(44): oap.org/soap/envelope/"><soapenv:Body><soapenv:Fault><faultcode>soapenv:Server</faultcode>
Action.c(44): <faultstring>Exception during creation of SOAP envelope structure</faultstring><detail><Ex
Action.c(44): ception>org.apache.axis2.AxisFault: Exception during creation of SOAP envelope structure\n
Action.c(44): \tat com.ibm.broker.axis2.Axis2Invoker.invokeAxis2(Axis2Invoker.java:2647)\n
Action.c(44): \tat com.ibm.broker.axis2.TomcatNodeRegistrationUtil.invokeAXIS2(TomcatNodeRegistrationUti
Action.c(44): l.java:474)\n
Action.c(44): Caused by: org.apache.axiom.om.OMException: Mime parts not found. Stream ended while searc
Action.c(44): hing for the boundary\n
Action.c(44): \tat org.apache.axiom.attachments.Attachments.&lt;init&gt;(Attachments.java:236)\n
Action.c(44): \tat org.apache.axiom.attachments.Attachments.&lt;init&gt;(Attachments.java:147)\n
Action.c(44): \tat org.apache.axiom.attachments.Attachments.&lt;init&gt;(Attachments.java:294)\n
Action.c(44): \tat com.ibm.broker.axis2.SoapUtilities.createSOAPMessage(SoapUtilities.java:1995)\n
Action.c(44): \tat com.ibm.broker.axis2.SoapUtilities.createSOAPMessage(SoapUtilities.java:1920)\n
Action.c(44): \tat com.ibm.broker.axis2.Axis2Invoker.invokeAxis2(Axis2Invoker.java:2642)\n
Action.c(44): \t... 1 more\n

Thanks,

Siva