Program creates the document but generates an error. Is there a way to resolve the error or identify what it stems from? System.InvalidOperationException: Cannot insert the OpenXmlElement "newChild" because it is part of a tree.

Hi All,

I had been trying to find a way to add a header to my document that worked and seemed simple enough for me.  I found a solution and tried to modifiy it to work with my program.  I created a smaller test version in order to attempt determining how well it worked.  After testing, it generated an error and crashed, however it still created the word document the way I desired (basically a document with a header and body text).  I attempted adding try/catches but removed them as you'll see below because it would still crash and say my exception message variables were null unless I did not try to extract the message from the exception variable.  I am using Visual Web Developer 2013 and OpenXML 2.5.  Any help is appreciated, I've only been using the OpenXML for about 2 weeks.

Thank you,

Mitch

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using DocumentFormat.OpenXml;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Wordprocessing;
namespace HASPOnline
{
    public class TestDoc2
    {
        public TestDoc2()
        {
                string documentPath = @"C:\Users\me\Desktop\HeaderFooterDocument.docx";
                using (WordprocessingDocument package = WordprocessingDocument.Create(documentPath, WordprocessingDocumentType.Document))
                {
                        AddParts(package);
                        MainDocumentPart mainPart = package.MainDocumentPart;
                        Body body = package.MainDocumentPart.Document.Body;
                        Paragraph paraDocType = body.AppendChild(new Paragraph());
                        //Create run thats hold text that will be added to the paragraph
                        Run runDocHeader = paraDocType.AppendChild(new Run());
                        RunProperties rpDocHdr = new RunProperties();
                        rpDocHdr.Append(new Bold());
                        FontSize fs = new FontSize();
                        fs.Val = new StringValue("40");
                        rpDocHdr.Append(fs);
                        runDocHeader.AppendChild<RunProperties>(rpDocHdr);
                        //Add text to the run
                        runDocHeader.AppendChild(new Text("Health and Safety Plan"));
                        //Title Area
                        Paragraph paraHaspTitle = body.AppendChild(new Paragraph());
                        Run runTitle = paraHaspTitle.AppendChild(new Run());
                        RunProperties runproperties = runTitle.AppendChild(new RunProperties(new Bold()));
                        runTitle.AppendChild(new CarriageReturn());//Drop down a line
                        runTitle.AppendChild(new Bold());//Add bold to text
                        runTitle.AppendChild(new Text("Title: ") { Space = SpaceProcessingModeValues.Preserve });
                        //Title text
                        Run runTitleActual = paraHaspTitle.AppendChild(new Run());
                        runTitleActual.AppendChild(new Text("Will hold string variable for title here."));
                        //add body with more content back to document
                        mainPart.Document.Append(body);
                }
        }
        private static void AddParts(WordprocessingDocument parent)
        {
            string headerText = "HASP#:                                                                Expiration Date:";
                var mainDocumentPart = parent.AddMainDocumentPart();
                GenerateMainDocumentPart().Save(mainDocumentPart);
                var documentSettingsPart = mainDocumentPart.AddNewPart<DocumentSettingsPart>("rId1");
                GenerateDocumentSettingsPart().Save(documentSettingsPart);
                var firstPageHeaderPart = mainDocumentPart.AddNewPart<HeaderPart>("rId2");
                GeneratePageHeaderPart(headerText).Save(firstPageHeaderPart);
                var evenPageHeaderPart = mainDocumentPart.AddNewPart<HeaderPart>("rId4");
                GeneratePageHeaderPart(headerText).Save(evenPageHeaderPart);
                var oddPageheaderPart = mainDocumentPart.AddNewPart<HeaderPart>("rId6");
                GeneratePageHeaderPart(headerText).Save(oddPageheaderPart);
        }
        private static Document GenerateMainDocumentPart()
        {
            var element =
                new Document(
                    new Body(
                        new SectionProperties(
                            new HeaderReference()
                            {
                                Type = HeaderFooterValues.First,
                                Id = "rId2"
                            },
                            new HeaderReference()
                            {
                                Type = HeaderFooterValues.Even,
                                Id = "rId4"
                            },
                            new HeaderReference()
                            {
                                Type = HeaderFooterValues.Default,
                                Id = "rId6"
                            },
                            new PageMargin()
                            {
                                Top = 1440,
                                Right = (UInt32Value)1440UL,
                                Bottom = 1440,
                                Left = (UInt32Value)1440UL,
                                Header = (UInt32Value)720UL,
                                Footer = (UInt32Value)720UL,
                                Gutter = (UInt32Value)0UL
                            },
                            new TitlePage()
                        )));
            return element;
        }
        private static Header GeneratePageHeaderPart(string HeaderText)
        {
            var element =
                new Header(
                    new Paragraph(
                        new ParagraphProperties(
                            new ParagraphStyleId() { Val = "Header" }),
                        new Run(
                            new Text(HeaderText))
                    ));
            return element;
        }
        private static Settings GenerateDocumentSettingsPart()
        {
            var element =
                new Settings(new EvenAndOddHeaders());
            return element;
        }
    }
}