Einfügen Arbeitsblatt mit Open XML - "...nicht lesbare Inhalte..."

Dass Fehlermeldung bedeutet, dass das XML, das macht Ihr excel-Dokument ist nicht konform zu dem XML-Schema und ist ungültig. Sie können die Open XML SDK 2.0 Productivity Tool, um zu sehen, wo das Problem liegt.

Ich auch kopiert den code aus dem unten von Ihrer Verbindung, und bekam es zu arbeiten, so wie Chris sagte in seinem Kommentar. Funktioniert Ihr code wie folgt Aussehen unten?

//Open the document for editing.
using (SpreadsheetDocument spreadSheet = SpreadsheetDocument.Open(docName, true)) 
{
    //Add a blank WorksheetPart.
    WorksheetPart newWorksheetPart = 
       spreadSheet.WorkbookPart.AddNewPart<WorksheetPart>();
    newWorksheetPart.Worksheet = new Worksheet(new SheetData());

    Sheets sheets = spreadSheet.WorkbookPart.Workbook.GetFirstChild<Sheets>();
    string relationshipId = 
       spreadSheet.WorkbookPart.GetIdOfPart(newWorksheetPart);
    //Get a unique ID for the new worksheet.
    uint sheetId = 1;
    if (sheets.Elements<Sheet>().Count() > 0)
    {
        sheetId = 
        sheets.Elements<Sheet>().Select(s => s.SheetId.Value).Max() + 1;
    }

    //Give the new worksheet a name.
    string sheetName = "Sheet" + sheetId;

    //Append the new worksheet and associate it with the workbook.
    Sheet sheet = new Sheet() 
    { Id = relationshipId, SheetId = sheetId, Name = sheetName };
    sheets.Append(sheet);

    string docName = @"C:\Users\Public\Documents\Sheet7.xlsx";
    InsertWorksheet(docName);
}

//Given a document name, inserts a new worksheet.
public static void InsertWorksheet(string docName)
{
    //Open the document for editing.
    using (SpreadsheetDocument spreadSheet = SpreadsheetDocument.Open(docName, true))
    {
        //Add a blank WorksheetPart.
        WorksheetPart newWorksheetPart = spreadSheet.WorkbookPart.AddNewPart<WorksheetPart>();
        newWorksheetPart.Worksheet = new Worksheet(new SheetData());

        Sheets sheets = spreadSheet.WorkbookPart.Workbook.GetFirstChild<Sheets>();
        string relationshipId = spreadSheet.WorkbookPart.GetIdOfPart(newWorksheetPart);

        //Get a unique ID for the new worksheet.
        uint sheetId = 1;
        if (sheets.Elements<Sheet>().Count() > 0)
        {
            sheetId = sheets.Elements<Sheet>().Select(s => s.SheetId.Value).Max() + 1;
        }

        //Give the new worksheet a name.
        string sheetName = "Sheet" + sheetId;

        //Append the new worksheet and associate it with the workbook.
        Sheet sheet = new Sheet() { Id = relationshipId, SheetId = sheetId, Name = sheetName };
        sheets.Append(sheet);
    }
}