While manipulating an XML file I came across with this exception and googled it out for solution. I found many stuffs but none of those were relevant and could not resolve my problem. After few minutes of analysis, I came to know that I was doing something wrong.
I was trying to add element directly to XML document, which was not correct. It should be added within the root element. I changed my code accordingly and it was resolved. Full XML file and C# code is given below. Hope this will be helpful for others, and please feel free to add comments or any queries.
XmlDocument doc = new XmlDocument();
// Create new element:
XmlElement book = doc.CreateElement("Book");
// Create child elements:
XmlElement title = docDestn.CreateElement("Title");
title.InnerText = "Mastering in ASP.Net 4.5";
XmlElement author = docDestn.CreateElement("Author");
title.InnerText = "Unknown Author";
XmlElement version = docDestn.CreateElement("Version");
title.InnerText = "V4.5";
// Read the root node:
XmlNode root = doc.SelectSingleNode("AllBooks");