xml - You must write ContentLength bytes to the request stream before calling [Begin]GetResponse -

error: must write contentlength bytes request stream before calling [begin]getresponse.

can advise why getting above error when running following code

        dim xml new system.xml.xmldocument()          dim root xmlelement         root = xml.createelement("root")         xml.appendchild(root)          dim username xmlelement         username = xml.createelement("username")         username.innertext = "xxxxx"         root.appendchild(username)          dim password xmlelement         password = xml.createelement("password")         password.innertext = "xxxx"         root.appendchild(password)          dim shipmenttype xmlelement         shipmenttype = xml.createelement("shipmenttype")         shipmenttype.innertext = "delivery"         root.appendchild(shipmenttype)           dim url = "xxxxxx"         dim req webrequest = webrequest.create(url)         req.method = "post"         req.contenttype = "application/xml"         req.headers.add("custom: api_method")         req.contentlength = xml.innerxml.length          dim newstream stream = req.getrequeststream()         xml.save(newstream)          dim response webresponse = req.getresponse()           console.write(response.tostring()) 

probably length mismatch between character length of xml.innerxml , written stream in xml.save(newstream). check if innerxml includes xml version node, example. also, don't see specifying character encoding, affects size on wire. perhaps need save temporary memory stream, length of that, , send in request.