.NET 3.5 SP1: DataContractJsonSerializer Bug

Update 9/16/2008: After too long, I finally tried uninstalling SP1 and reinstalling it and that fixed the issue. I’m glad it’s fixed now! I haven’t seen any other suggestions for fixing this, and I first tried repairing the installation, but only an uninstall and reinstall fixed it. Hope this helps solves anyone elses headache with this issue.

A few months ago (back in February actually) I blogged showing how to use the new DataContractJsonSerializer to serialize your .NET objects to JSON. Everything was fine until .NET 3.5 SP1 was released. It appears that the .NET 3.5 SP1 update breaks the DataContractJsonSerializer. Using the exact same code from my previous post that worked perfect on .NET 3.5 RTM, breaks with the following exceptions in .NET 3.5 SP1 RTM:

First Exception

This exception occurrs when running this code within a Console application:

System.MissingFieldException was unhandled
  Message="Field not found: 'System.Runtime.Serialization.XmlObjectSerializerContext.serializerKnownDataContracts'."
  Source="System.ServiceModel.Web"
  StackTrace:
       at System.Runtime.Serialization.Json.XmlObjectSerializerWriteContextComplexJson..ctor(DataContractJsonSerializer serializer, DataContract rootTypeDataContract)
       at System.Runtime.Serialization.Json.DataContractJsonSerializer.InternalWriteObjectContent(XmlWriterDelegator writer, Object graph)
       at System.Runtime.Serialization.Json.DataContractJsonSerializer.InternalWriteObject(XmlWriterDelegator writer, Object graph)
       at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator writer, Object graph)
       at System.Runtime.Serialization.Json.DataContractJsonSerializer.WriteObject(XmlDictionaryWriter writer, Object graph)
       at System.Runtime.Serialization.Json.DataContractJsonSerializer.WriteObject(Stream stream, Object graph)
       at JsonSerializer_dotNet35SP1_IssueTest.JSONHelper.Serialize[T](T obj) in D:\TEST\JsonSerializer_dotNet35SP1_IssueTest\JsonSerializer_dotNet35SP1_IssueTest\Program.cs:line 56
       at JsonSerializer_dotNet35SP1_IssueTest.Program.Main(String[] args) in D:\TEST\JsonSerializer_dotNet35SP1_IssueTest\JsonSerializer_dotNet35SP1_IssueTest\Program.cs:line 22
       at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

**Code for Console app: **

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Runtime.Serialization;
//using System.ServiceModel.Web;

namespace JsonSerializer_dotNet35SP1_IssueTest
{
    public class Program
    {
        static void Main(string[] args)
        {

            /// Sample code using the above helper methods
            /// to serialize and deserialize the Person object

            Person myPerson = new Person("Chris", "Pietschmann", 26);

            // Serialize
            string json = JSONHelper.Serialize(myPerson);

            // Deserialize
            myPerson = JSONHelper.Deserialize(json);
        }
    }

    [DataContract]
    public class Person
    {
        public Person() { }
        public Person(string firstname, string lastname, int age)
        {
            this.FirstName = firstname;
            this.LastName = lastname;
            this.Age = age;
        }

        [DataMember]
        public string FirstName { get; set; }

        [DataMember]
        public string LastName { get; set; }

        [DataMember]
        public int Age { get; set; }
    }

    public class JSONHelper
    {
        public static string Serialize(T obj)
        {
            System.Runtime.Serialization.Json.DataContractJsonSerializer serializer = new System.Runtime.Serialization.Json.DataContractJsonSerializer(obj.GetType());
            MemoryStream ms = new MemoryStream();
            serializer.WriteObject(ms, obj);
            string retVal = Encoding.Default.GetString(ms.ToArray());
            return retVal;
        }

        public static T Deserialize(string json)
        {
            T obj = Activator.CreateInstance();
            MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(json));
            System.Runtime.Serialization.Json.DataContractJsonSerializer serializer = new System.Runtime.Serialization.Json.DataContractJsonSerializer(obj.GetType());
            obj = (T)serializer.ReadObject(ms);
            ms.Close();
            return obj;
        }
    }
} </pre>
## Second Exception

This exception occurrs when running this code within an ASP.NET WebPage:
System.MissingMethodException was unhandled by user code
  Message="Method not found: 'Boolean System.Runtime.Serialization.DataContract.get_IsReference()'."
  Source="System.ServiceModel.Web"
  StackTrace:
       at System.Runtime.Serialization.Json.DataContractJsonSerializer.CheckIfTypeIsReference(DataContract dataContract)
       at System.Runtime.Serialization.Json.DataContractJsonSerializer.get_RootContract()
       at System.Runtime.Serialization.Json.DataContractJsonSerializer.InternalWriteObjectContent(XmlWriterDelegator writer, Object graph)
       at System.Runtime.Serialization.Json.DataContractJsonSerializer.InternalWriteObject(XmlWriterDelegator writer, Object graph)
       at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator writer, Object graph)
       at System.Runtime.Serialization.Json.DataContractJsonSerializer.WriteObject(XmlDictionaryWriter writer, Object graph)
       at System.Runtime.Serialization.Json.DataContractJsonSerializer.WriteObject(Stream stream, Object graph)
       at _Default.JSONHelper.Serialize[T](T obj) in d:\TEST\JsonSerializer_dotNet35SP1_IssueTest_ASPNET\Default.aspx.cs:line 55
       at _Default.Page_Load(Object sender, EventArgs e) in d:\TEST\JsonSerializer_dotNet35SP1_IssueTest_ASPNET\Default.aspx.cs:line 22
       at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)
       at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e)
       at System.Web.UI.Control.OnLoad(EventArgs e)
       at System.Web.UI.Control.LoadRecursive()
       at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  InnerException:

**Code for ASP.NET app:**
using System;
using System.IO;
using System.Runtime.Serialization;
using System.Text;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

        /// Sample code using the above helper methods
        /// to serialize and deserialize the Person object

        Person myPerson = new Person("Chris", "Pietschmann", 26);

        // Serialize
        string json = JSONHelper.Serialize(myPerson);

        // Deserialize
        myPerson = JSONHelper.Deserialize(json);
    }

    [DataContract]
    public class Person
    {
        public Person() { }
        public Person(string firstname, string lastname, int age)
        {
            this.FirstName = firstname;
            this.LastName = lastname;
            this.Age = age;
        }

        [DataMember]
        public string FirstName { get; set; }

        [DataMember]
        public string LastName { get; set; }

        [DataMember]
        public int Age { get; set; }
    }

    public class JSONHelper
    {
        public static string Serialize(T obj)
        {
            System.Runtime.Serialization.Json.DataContractJsonSerializer serializer = new System.Runtime.Serialization.Json.DataContractJsonSerializer(obj.GetType());
            MemoryStream ms = new MemoryStream();
            serializer.WriteObject(ms, obj);
            string retVal = Encoding.Default.GetString(ms.ToArray());
            return retVal;
        }

        public static T Deserialize(string json)
        {
            T obj = Activator.CreateInstance();
            MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(json));
            System.Runtime.Serialization.Json.DataContractJsonSerializer serializer = new System.Runtime.Serialization.Json.DataContractJsonSerializer(obj.GetType());
            obj = (T)serializer.ReadObject(ms);
            ms.Close();
            return obj;
        }
    }
}</pre>
## WTF??

I searched for a possible solution, but the only thing I found was this link (http://forums.msdn.microsoft.com/en-US/csharpgeneral/thread/37558154-88a9-41f0-a9d6-a2cb4052a5ce/) where someone mentions the First Exception above. The suggested solution was to use the KnownType Attribute on the object, but that doesn't help with my above code.

Does anyone know a work around for this that doesn't involve using the older JavaScriptSerializer object?

Well, for now, it looks like I'm almost the only one to experience this issue.