Scott Hanselman

HOW TO: Debug into a .NET XmlSerializer Generated Assembly

November 06, 2004 Comment on this post [0] Posted in ASP.NET | XmlSerializer | Bugs
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The XmlSerializer is a much maligned piece of software, but I have to tell you, it's the bomb.  We use it a lot here at Corillian. Recently we had to debug a pretty funky problem where an enum was writing out to an XML file, but wasn't reading back in. We suspected it was a namespace thing, but the XmlSerializer is such a black box, a lot of people really have trouble dealing with it. It inspires a trial-and-error style, while I prefer to debug and step around myself.

Here's how to debug into a generated assembly from the XmlSerializer.

1. Given an application like:

using System.Xml;
using System.Xml.Serialization;
using System.Text;
using System.IO;

namespace Foo
    public class Bar
        public static void Main(string[] args)
            XmlSerializer x = new XmlSerializer(typeof(Person));
            Person p = new Person();
            p.first = "Scott";
            p.last = "Hanselman";
            x.Serialize(new StreamWriter("foo.xml"),p);

    public class Person
        public string first;
        public string last;

2. Create a yourapplication.exe.config like this:

<?xml version="1.0" encoding="utf-8" ?>
         <add name="XmlSerialization.Compilation" value="1" />

3. Compile and run and step up to the line where the XmlSerializer is constructed, and step over that line.

4. Go to c:\documents and settings\[username]\local settings\temp and look at the most recently created *.cs file. Open that file, it will have a name like asdasdfs.0.cs. Note that there are *.pdbs in that folder as well.

5. Set a breakpoint anywhere in that generated file.

6. Debug to taste (see screenshot below)

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Disclaimer: The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.