Namespace Manager or XsltContext needed. This query has a prefix, variable, or user-defined function

Question

I am trying to call SelectNode from XmlDocument class and trouble due to this error:

Namespace Manager or XsltContext needed

Answer 1

You have to add xsl namespace to XmlNamespaceManager:

var document = new XmlDocument();
document.Load(...);
var nsmgr = new XmlNamespaceManager(document.NameTable);
nsmgr.AddNamespace("xsl", "http://www.w3.org/1999/XSL/Transform");

var nl = document.SelectNodes("//xsl:import/@href", nsmgr);

Answer 2

The document can be traversed by GetElementsByTagName and it doesn't necessarily need using XmlNamespaceManager:

var nodes = document.GetElementsByTagName("xsl:import");
var href =  nodes[0].Attributes["href"];

Fiddle