I have the code sample shown below:

When I run the line "request.GetRequestStream()" get called it takes long time before the control comes back to the program and then when this line "Dim response As HttpWebResponse = DirectCast(request.GetResponse(), HttpWebResponse)" get executed, system is giving errors as shown below:

The underlying connection was closed: An unexpected error occurred on a receive.

StatusCode BadRequest {400} System.Net.HttpStatusCode
StatusDescription "Bad Request" String

For _SessionID, I am passing the session ID which I get by calling the login with Soap and then that session ID is passed to the code below as per documentation. 

For _ServerUrl, I tried to use my QA link: { https://tapp0-api.salesforce.com/services/async/25.​0/job}  as well as for prod:  {https://na6.salesforce.com/services/async/25.​0/job}

and in both cases I am getting the above error.

By the way the error handling is not getting executed since this "

If e.Response IsNot Nothing Then

is always returning nothing for e.Response.

Here is the code sample:

=============================

Dim request As HttpWebRequest = DirectCast(HttpWebRequest.Create(_ServerUrl), HttpWebRequest)
request.Method = WebRequestMethods.Http.Post
request.ContentType = "application/xml; charset=UTF-8"
request.Headers.Add("X-SFDC-Session", _SessionID)
request.KeepAlive = False
''request.Host = "na6.salesforce.com"
request.Host = "tapp0-api.salesforce.com"
request.UserAgent = ".NET Framework Test Client"
request.Accept = "application/xml"
Dim body As String = ""body += "<?xml version=""1.0"" encoding=""UTF-8""?>"
body += "<jobInfo xmlns=""http://www.force.com/2009/06/asyncapi/dataload"">"
body += "<operation>insert</operation>"
body += "<object>Account</object>"
body += "<contentType>CSV</contentType>"
body += "</jobInfo>"
Dim strErrorMessage As String = ""
Dim byteArray As Byte() = Encoding.UTF8.GetBytes(body)
request.ContentLength = byteArray.Length
request.Timeout = 5000
ServicePointManager.ServerCertificateValidationCallback = New System.Net.Security.RemoteCertificateValidationCallback(AddressOf customXertificateValidation)
Try
Dim datastream As Stream = request.GetRequestStream()
datastream.Write(byteArray, 0, byteArray.Length)
datastream.Close()
Catch ex As Exception
strErrorMessage = ex.Message
End Try
 
Dim responseFromServer As String
Try
'Call the service and get the response
Dim response As HttpWebResponse = DirectCast(request.GetResponse(), HttpWebResponse) ''Failes on this line
If HttpStatusCode.OK = response.StatusCode Then
Dim dataStream2 As Stream = response.GetResponseStream()
Dim reader As New StreamReader(dataStream2)
responseFromServer = reader.ReadToEnd()
response.Close()
End If
request.Abort()
Catch e As WebException
If e.Response IsNot Nothing Then
Using response As WebResponse = e.Response
Dim httpResponse As HttpWebResponse = DirectCast(response, HttpWebResponse)
responseFromServer = String.Format("Error code: {0} ", httpResponse.StatusCode)
Using data As Stream = response.GetResponseStream()
responseFromServer += New StreamReader(data).ReadToEnd()
Return responseFromServer
End Using
End Using
End If
request.Abort()
End Try

=============================