Why “Data at the root level is invalid. Line 1, position 1.” for XML Document?

Question

I am using a third-party DLL which transmits an XML document over the internet.

Why would the DLL be throwing the following exception?

Data at

Answer 1

I eventually figured out there was a byte mark exception and removed it using this code:

 string _byteOrderMarkUtf8 = Encoding.UTF8.GetString(Encoding.UTF8.GetPreamble());
    if (xml.StartsWith(_byteOrderMarkUtf8))
    {
        var lastIndexOfUtf8 = _byteOrderMarkUtf8.Length-1;
        xml = xml.Remove(0, lastIndexOfUtf8);
    }