400 错误请求：XML 文档中有错误 (1, 1254) 消息显示不正确的行号

Question

I am sending a request to external API from my application using HttpWebRequest and HttpWebResponse.

Whenever there is an error in XML request due to some wrong values passed in XML nodes, then there is a 400 Bad request error response and the error message is "There is an error in XML document (51, 14)". The problem is if there is an error in request XML, the response XML should display the error message with correct line number. but I am receiving an error message with incorrect line number and it is always "There is an error in XML document (1, 1254)". There is actually no error at line 1. Due to this issue, I have no chance to point to the error when troubleshooting.

Can you help how do I get Response with the correct line number in XML.

Below is my existing code in vb to send the request to API.

Dim Wreq As HttpWebRequest
Dim MyURI As String = String.Empty
Dim bytes() As Byte
Try
MyURI = p_strURL
Wreq = HttpWebRequest.Create(MyURI)
Wreq.Method = "POST"
bytes = System.Text.Encoding.UTF8.GetBytes(pi_strRequestXML)
Wreq.ContentLength = bytes.Length 'pi_strRequestXML.Length
Wreq.ContentType = "application/x-www-form-urlencoded"
Wreq.KeepAlive = False
Wreq.Headers.Add("Authorization", "bearer" + " " + strAccessToken)
Using OutputStream As StreamWriter = New StreamWriter(Wreq.GetRequestStream())
OutputStream.Write(pi_strRequestXML)
End Using

Using Wres As HttpWebResponse = Wreq.GetResponse()
Using loResponseStream As StreamReader = New StreamReader(Wres.GetResponseStream())
oResponse = loResponseStream.ReadToEnd()
End Using
End Using
Return oResponse
Catch e As WebException
Throw
Catch objSysEx As Exception
Throw
Finally

End Try

Thanks

Answer 1

Finally, I could find and solve this issue. The problem was in request XML that I was trying to send. Request XML is not correctly formatted and so it was showing inappropriate line numbers if there is an error in XML. The solution for this was to format request XML with proper indentation. Below is the code I used to make well-formatted XML.

Using sw As New StringWriterWithEncoding(Encoding.UTF8)
    Using tw As New XmlTextWriter(sw)
     'tw.Settings.Encoding = Encoding.UTF8
      tw.Formatting = Xml.Formatting.Indented
      tw.Indentation = 4
      Dim docu As New XmlDocument
      docu.LoadXml(strXML)
      docu.Save(tw)
      strProfileXML = Convert.ToString(sw)
   End Using
End Using

in above code, StringWriterWithEncoding is the function that is used to create formatted XML with UTF-8 encoding. if not used this function then XML will be created with UTF-16

Below is the function to use to set encoding for XML

Private NotInheritable Class StringWriterWithEncoding
        Inherits StringWriter
        Private ReadOnly m_encoding As Encoding
        Public Sub New(encoding As Encoding)
            m_encoding = encoding
        End Sub
        Public Overloads Overrides ReadOnly Property Encoding() As Encoding
            Get
                Return m_encoding
            End Get
        End Property
    End Class