how to ignore namespaces with XPath

You can use the local-name() XPath function. Instead of selecting a node like

/path/to/x:somenode

you can select all nodes and filter for the one with the correct local name:

/path/to/*[local-name() = 'somenode']

You can do the same In XPath2.0 in a less verbose syntax:

/path/to/*:somenode

You could use Namespace = false on a XmlTextReader

[TestMethod]public void MyTestMethod(){    string _withXmlns = @"<?xml version=""1.0"" encoding=""utf-8""?><ParentTag xmlns=""http://anyNamespace.com""><Identification value=""ID123456"" /></ParentTag>";    var xmlReader = new XmlTextReader(new MemoryStream(Encoding.Default.GetBytes(_withXmlns)));    xmlReader.Namespaces = false;    var content = XElement.Load(xmlReader);    XElement elem = content.XPathSelectElement("/Identification");    elem.Should().NotBeNull();    elem.Attribute("value").Value.Should().Be("ID123456");}

with :

using System;using System.IO;using System.Linq;using System.Text;using System.Xml;using System.Xml.Linq;using System.Xml.XPath;using FluentAssertions;using Microsoft.VisualStudio.TestTools.UnitTesting;