过时的成员.Net Framework 4.0

Question

我们将代码从.Net Framework 2.0迁移到.Net Framework 4.0，但是当我们测试它时，我们遇到了一个错误，即“对象引用未设置为实例对象”。

我们试图为此寻找可能的解决方案，并看到了有关.Net Framework 4.0 https://msdn.microsoft.com/en-us/library/ee471421(v=vs.100).aspx的过时类型和成员的文章。列在那里的成员之一正在我们的一个类中使用，即“System.Xml.Serialization.XmlSerializer”，但即使我们继续构建我们的解决方案，也没有发现错误。这真的是一个过时的成员/类型的行为？或者您认为“对象引用未设置为实例对象”的错误与这些过时的成员/类型有关吗？

        #region Variables Setup
        //Declare Variables
        string orderUID = string.Empty;
        string input = string.Empty;

        APSArchitecture.Tools.APSLogData logData = null;
        XmlDocument bodyDoc = null;
        IBaseMessagePart bodyPart = null;
        const string APSHEADER_PARTNAME = "APSHeader";
        APSArchitecture.Tools.Serialization.APSHeader apsHeader = null;         
        APSArchitecture.Pipelines.NonSeekMemoryStream APSHdrStream = null;
        APSArchitecture.Pipelines.NonSeekMemoryStream copyOfBodyStream = null;
        **XmlSerializer serializer** = null;
        Microsoft.BizTalk.Message.Interop.IBaseMessagePart part = null;
        string partname = string.Empty;
        XmlNamespaceManager nsmgr = null;
        Stream originalBodyStream = null;
        #endregion

        #region Init Variables
        //Initial Variables
        try 
        {
            logData = new APSArchitecture.Tools.APSLogData();
            logData.SrcSystem = "AssignOrderUID.Execute";
            bodyDoc = new XmlDocument();
            bodyPart = pInMsg.BodyPart;
            originalBodyStream = bodyPart.Data;
            copyOfBodyStream = new NonSeekMemoryStream();
            //
            // Copy the original message to the copy stream for reading of the xml.
            //
            const int ONE_K = 1024;
            byte[] buffer = new byte[ONE_K];
            int readSize = 0;
            while((readSize = originalBodyStream.Read(buffer,0,ONE_K)) != 0)
            {
                copyOfBodyStream.Write(buffer,0,readSize);
            }
            copyOfBodyStream.Seek(0,SeekOrigin.Begin);
        }
        catch(System.Exception ex)
        {
            string error = ex.Message;
            if(ex.InnerException != null)
                error = error + " Inner Exception Details: " + ex.InnerException.Message;
            throw new ApplicationException("Error initilalizing AssignOrderUID Execute method. Exception Details: " + error, ex);
        }