C# Excel interop: Exception from HRESULT (DISP_E_BADINDEX)

Question

I'm trying to deploy an application that works fine on my development pc and some other workstations. However, some users receive an error that I can't seem to grasp.

The program is a C# dotNet app with Excel.Interop functionality (Office 2003).

I seem to be getting a problem with 'indexes'. The weird thing is that this part works perfect on some machines but throws a fatal exception on others... All machines are Windows 7 with Office 2003.

This is the relevant code:

//Change sheet code (index is 1, 2, 3) -> errors at #2
public void ChangeWorksheet(int sheetIndex)
{
    if (_OnXLSEvent != null) _OnXLSEvent(string.Format("TEMP: working on page {0}", sheetIndex));
    _WS = _WSs[sheetIndex];
    _Shapes = _WS.Shapes;
    _PageSetup = _WS.PageSetup;
    if (_OnXLSEvent != null) _OnXLSEvent(string.Format("TEMP: working on page {0}", _WS.Name));
}

//Constructor (_App and _WBs are static)
public ExcelProcessor(bool SaveAutomatically = false, string SavePath = "")
{
    if (_App == null)
        _App = new XLS.Application();
    if (_WBs == null)
        _WBs = _App.Workbooks;
    _WB = _WBs.Add();
    _WSs = _WB.Sheets;
    _WS = _WSs[1];
    _Shapes = _WS.Shapes;
    _PageSetup = _WS.PageSetup;
    _SavePath = SavePath;
    _SaveOnDispose = SaveAutomatically;
    _App.DisplayAlerts = false;
    ApplyPageSetup();
}

This is the log that I'm receiving:

... Irrelevant
8:52:   TEMP: working on page 1
8:52:   TEMP: working on page Sheet1
8:52:   TEMP: working on page 2
8:52:   Error occurred:
Invalid index. (Exception from HRESULT: 0x8002000B (DISP_E_BADINDEX))
at Microsoft.Office.Interop.Excel.Sheets.get__Default(Object Index)
at Classes.XLSInterop.ExcelProcessor.ChangeWorksheet(Int32 sheetIndex) in     c:\Users\panjaj\Documents\VS Projects\Projects\Client   Projects\ProFormaCreator\ProFormaCreator\Classes\XLSInterop\ExcelProcessor.cs:line 74
at Classes.ApplicationManager.Manager.ProcessSingleDocument(InFileDocument doc) in c:\Users\panjaj\Documents\VS Projects\Projects\Client Projects\ProFormaCreator\ProFormaCreator\Classes\ApplicationManager\ApplicationManager.cs:line 327
at Classes.ApplicationManager.Manager.ConvertFile(String File) in c:\Users\panjaj\Documents\VS Projects\Projects\Client Projects\ProFormaCreator\ProFormaCreator\Classes\ApplicationManager\ApplicationManager.cs:line 172

Answer 1

I spoke too soon! This is just a really dumb error. I thought I'd give the solution so others might not fall into the same trap as I did ;-)

To analyse the problem further, I added following code to the constructor:

List<XLS.Worksheet> sheets = new List<XLS.Worksheet>()
foreach(XLS.Worksheet sh in _WSs)
{
    sheets.Add(sh);
}
if(_OnXLSEvent != null) _OnXLSEvent(String.Format("\n\tSheets in WB: {0}\n\tFirst Sheet index: {1}, \n\tLast Sheet index: {2}",
                                                  _WSs.Count,
                                                  sheets[0].Index,
                                                  sheets.Last().Index));

This resulted in following log on my machine:

Sheets in WB: 3
First Sheet index: 1, 
Last Sheet index: 3

But in following log on the target machine:

Sheets in WB: 1
First Sheet index: 1, 
Last Sheet index: 1

Conclusion: the amount of worksheets that are standard added to a new workbook differ from user to user. Something to keep in mind!

Answer 2

You can check if worksheets are not present then add them. Usually first worksheet is created by default and you can check rest as below. I had similar issue and resolved as below.

           // Add Worksheet 2 if not present
            if (workbook.Worksheets.Count < 2)
            {
                workbook.Worksheets.Add();
            }

            // Add Worksheet 3 if not present
            if (workbook.Worksheets.Count < 3)
            {
                workbook.Worksheets.Add();
            }