Develop Reference

C# Error: Microsoft Excel cannot access the file '...'. There are several possible reasons

I've developed an ASP.Net MVC application, that is running on a IIS sever. I've wrote a code that reads a CSV and insert the rows of it in a database.
[HttpPost]
public ActionResult InsertPosition(int id, HttpPostedFileBase position)
{
var posicoesExistentes = db.tbPositions.Where(s => s.id_unique == id).AsEnumerable();
foreach (tbPosition posicao in posicoesExistentes)
{
db.tbPositions.Remove(posicao);
}
if (!Directory.Exists(Server.MapPath("~/App_Data/")))
{
System.IO.Directory.CreateDirectory(Server.MapPath("~/App_Data/"));
}
string excelPath = Server.MapPath("~/App_Data/" + position.FileName);
if (System.IO.File.Exists(excelPath))
{
System.IO.File.Delete(excelPath);
}
position.SaveAs(excelPath);
string tempPath = Server.MapPath("~/App_Data/" + "tmp_" + position.FileName);
System.IO.File.Copy(excelPath, tempPath, true);
Excel.Application application = new Excel.Application();
Excel.Workbook workbook = application.Workbooks.Open(tempPath, ReadOnly: true,Editable:false);
Excel.Worksheet worksheet = workbook.ActiveSheet;
Excel.Range range = worksheet.UsedRange;
application.Visible = true;
for (int row = 1; row < range.Rows.Count - 1; row++)
{
tbPosition p = new tbPosition();
p.position = (((Excel.Range)range.Cells[row, 1]).Text == "") ? null : Convert.ToInt32(((Excel.Range)range.Cells[row, 1]).Text);
p.left = ((Excel.Range)range.Cells[row, 2]).Text;
p.right = ((Excel.Range)range.Cells[row, 3]).Text;
p.paper = ((Excel.Range)range.Cells[row, 4]).Text;
p.denomination = ((Excel.Range)range.Cells[row, 5]).Text;
p.material = ((Excel.Range)range.Cells[row, 6]).Text;
p.norme = ((Excel.Range)range.Cells[row, 7]).Text;
p.finalized_measures = ((Excel.Range)range.Cells[row, 8]).Text;
p.observation = ((Excel.Range)range.Cells[row, 9]).Text;
p.id_unique = id;
db.tbPositions.Add(p);
db.SaveChanges();
}
workbook.Close(true, Type.Missing, Type.Missing);
application.Quit();
System.IO.File.Delete(tempPath);
return Json("Success", JsonRequestBehavior.AllowGet);
}
but in return I got the error ' Microsoft Excel cannot access the file '...'. There are several possible reasons' when I try to open the requested excel file.
I've already tried to open the file as readonly, I've already tried to give permissions to the specifieds folders, multiples ways of close the excel file, and create an copy file of the original and read him. But unsuccessful in each one of these solutions. What have I missed here?

Unsupported
The short answer is that trying to programatically manipulate an Excel document using the Automation API is not supported outside of a UI context. You will come across all sorts of frustrations (for example, the API is permitted to show dialogs - how are you going to click on "OK" if it's running on a web-server?).
Microsoft explicitly state this here
Microsoft does not recommend or support server-side Automation of Office.
So what do I use?
I would recommend using the OpenXML SDK - this is free, fully supported and much faster than the Automation API.
Aspose also has a set of products, but they are not free, and I've not used them.
But I HAVE to do it this way
However, if you absolutely have to use the COM API then the following might help you:
HERE BE DRAGONS
The big problem with automation in Excel is that you need to ensure you close every single reference whenever you use them (by calling ReleaseComObject on it).
For example, the following code will cause Excel to stay open:
var range;
range = excelApplication.Range("A1");
range = excelApplication.Range("A2");
System.Runtime.InteropServices.Marshal.ReleaseComObject(range)
range = Nothing
This is because there is still a reference left over from the call to get range "A1".
Therefore, I would recommend writing a wrapper around the Excel class so that any access to, e.g., a range frees any previous ranges accessed before accessing the new range.
For reference, here is the code I used to release COM objects in the class I wrote:
Private Sub ReleaseComObject(ByVal o As Object)
Try
If Not IsNothing(o) Then
While System.Runtime.InteropServices.Marshal.ReleaseComObject(o) > 0
'Wait for COM object to be released.'
End While
End If
o = Nothing
Catch exc As System.Runtime.InteropServices.COMException
LogError(exc) ' Suppress errors thrown here '
End Try
End Sub

Try this
protected void ImportCSV(object sender, EventArgs e)
{
importbtn();
}
public class Item
{
public Item(string line)
{
var split = line.Split(',');
string FIELD1 = split[0];
string FIELD2 = split[1];
string FIELD3 = split[2];
string mainconn = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
using (SqlConnection con = new SqlConnection(mainconn))
{
using (SqlCommand cmd = new SqlCommand("storedProcedureName", con))
{
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("#FIELD1", SqlDbType.VarChar).Value = FIELD1;
cmd.Parameters.AddWithValue("#FIELD2", SqlDbType.VarChar).Value = FIELD2;
cmd.Parameters.AddWithValue("#FIELD3", SqlDbType.VarChar).Value = FIELD3;
con.Open();
cmd.ExecuteNonQuery();
}
}
}
}
private void importbtn()
{
try
{
string csvPath = Server.MapPath("~/Files/") + Path.GetFileName(FileUpload1.PostedFile.FileName);
FileUpload1.SaveAs(csvPath);
var listOfObjects = File.ReadLines(csvPath).Select(line => new Item(line)).ToList();
DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[3] { new DataColumn("FIELD1", typeof(string)),
new DataColumn("FIELD2", typeof(string)),
new DataColumn("FIELD3",typeof(string)) });
string csvData = File.ReadAllText(csvPath);
foreach (string row in csvData.Split('\n'))
{
if (!string.IsNullOrEmpty(row))
{
dt.Rows.Add();
int i = 0;
//Execute a loop over the columns.
foreach (string cell in row.Split(','))
{
dt.Rows[dt.Rows.Count - 1][i] = cell;
i++;
}
}
}
GridView1.DataSource = dt;
GridView1.DataBind();
Label1.Text = "File Attached Successfully";
}
catch (Exception ex)
{
Message.Text = "Please Attach any File" /*+ ex.Message*/;
}
}

Why is EPPlus Throwing Null Reference Exception on Accessing Workbook

I am coding in C# .NET Core 2.2. I am trying to replace Excel Interop with EPPlusCore in my code for reliability and for portablilty. I have a series of invoices I am opening with EPPlus, but some of them throw a "Null Reference" exception when accessing the Workbook property of the Excel package.
This only happens when running the code without debugging it. When debugging, if I hover over the ExcelPackage item, it refreshes the reference to the Workbook and I am able to run the rest of the code.
public object[,] GetExcelDataEpplus(string filePath, int index,
bool sheetByName = false, string name = null, string password = null)
{
var remoteFileInfo = new FileInfo(filePath);
if (!remoteFileInfo.Exists)
{
throw new Exception("File does not exist: " + filePath);
}
var currentPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "temp-excel");
if (!Directory.Exists(currentPath))
{
Directory.CreateDirectory(currentPath);
}
var localFileInfo = new FileInfo(Path.Combine(currentPath, remoteFileInfo.Name));
if (!localFileInfo.Exists)
{
File.Copy(filePath, localFileInfo.FullName);
}
object[,] values = null;
try
{
if (!File.Exists(localFileInfo.FullName))
{
_logger.LogInformation(DbLog, "Cannot find file : " + localFileInfo.FullName);
return null;
}
else
{
_logger.LogInformation(DbLog, "Found file : " + localFileInfo.FullName);
}
_logger.LogInformation(DbLog, "Initializing EPPlus...");
using (var package = string.IsNullOrEmpty(password)
? new ExcelPackage(localFileInfo)
: new ExcelPackage(localFileInfo, password))
{
_logger.LogInformation(DbLog, "Opening Workbook...");
//todo Error Thrown Here
try
{
package.Workbook.FormulaParserManager.LoadFunctionModule(new ImporterFunctionModule());
}
catch (Exception e)
{
_logger.LogWarning(DbLog, e, $"Could not load workbook : Loading file again...");
try
{
System.Threading.Thread.Sleep(1000);
package.Workbook.FormulaParserManager.LoadFunctionModule(new ImporterFunctionModule());
}
catch (Exception ex)
{
_logger.LogError(DbLog, ex, "Could not load workbook");
throw;
}
}
var workbook = package.Workbook;
_logger.LogInformation(DbLog, $"Calculating formulas...");
workbook.Calculate();
_logger.LogInformation(DbLog, "Finding Worksheet...");
var worksheet = sheetByName ? workbook.Worksheets.FirstOrDefault(x => x.Name == name) : workbook.Worksheets[index];
if (worksheet == null)
{
throw new Exception($"Could not find worksheet : {name}");
}
_logger.LogInformation(DbLog, $"Reading from worksheet : {worksheet.Name}...");
var start = worksheet.Dimension.Start;
var end = worksheet.Dimension.End;
values = worksheet.Cells[start.Row, start.Column, end.Row, end.Column].ToMultiDimensionalArray();
}
}
catch (Exception e)
{
_logger.LogError(DbLog, e, $"GetExcelInvoiceDataEpplus from {filePath} ({localFileInfo.FullName})"); //todo propogate error
}
finally
{
File.Delete(localFileInfo.FullName);
}
var rowCount = values?.GetLength(0) ?? 0;
_logger.LogInformation(DbLog, $"EPPLus found {rowCount} rows in the spreadsheet");
return values;
}
On most files, this works correctly, and I get a multidimensional array of the values from the specified worksheet tab. However, on some files, it does not work and I am at a loss as to why.
The closest similar problem I've been able to find is this: https://github.com/JanKallman/EPPlus/issues/416
But if this is accurate, how would I know what worksheet names have bad references without accessing the workbook first?

I found the solution. The excel files that were having problems were ones that were larger than average.
The solution was just to wait longer for them.
try
{
package.Workbook.FormulaParserManager.LoadFunctionModule(new ImporterFunctionModule());
}
catch (Exception e)
{
for (var i=1; i < 6; i++)
{
_logger.LogWarning(DbLog, e, $"Could not load workbook : Loading file again (Attempt #{i})...");
try
{
System.Threading.Thread.Sleep(2000);
package.Workbook.FormulaParserManager.LoadFunctionModule(new ImporterFunctionModule());
break;
}
catch (Exception ex)
{
if (i < 5) continue;
_logger.LogError(DbLog, ex, "Could not load workbook after 5 attempts");
throw;
}
}
}

c# - How to make excel auto calculate formula type cells

I have an excel file that has around 40 to 50 sheets of size 8mb and will be increasing may be 15 to 20mb and many are inter-linked with multiple formulas.
So basically if one cell values changes then it will affect multiple sheets because of function and vlookup's etc.
Now I am trying to manipulate the excel sheet dynamically using c#. But I see that the are not calculating instantly.
I tried using ExcelLibrary's Calculate function to do this.
Problems with ExcelLibrary are:
a. It is very very slow with Calculate, ExcelPackage(Open) and Save functions**(Makes it unusable)**.
b. Need to know all the dependent cell to trigger calculate on them(not preferring workbook or worksheet calculate(the debugger never comes to next line)) which is not efficient way to manage code in feature.
I believe the problem is because it works with ooxml and actually not directly with excel(not sure we can work with excel directly so that it will be like inserting data manually using code).
Note: Trying to test with Excel interop(hoping it will do the job because it opens excel file in background while manipulating.)
private void TestExcelWithSimultaneousReadOfTwoSheetsFromFile(string fileName)
{
try
{
int count = 0;
int rowIndex = 1702;
for (int rowCount = 0; rowCount < 3; rowCount++)
{
count = ReadCountFromProdReport(fileName);
WriteRowToProd(fileName, rowIndex + rowCount);
count = ReadCountFromProdReport(fileName);
}
}
catch (Exception ex)
{
throw ex;
}
}
private void WriteRowToProd(string fileName, int rowIndex)
{
try
{
string logDirectory = System.Configuration.ConfigurationManager.AppSettings["LogDirectory"].ToString().Trim();
string filePath = logDirectory + fileName + ConfigurationManager.AppSettings["ExcelSaveFileExtension"].ToString().Trim();
using (ExcelPackage excelPackage = new ExcelPackage(new FileInfo(filePath)))
{
foreach (ExcelWorksheet workSheet in excelPackage.Workbook.Worksheets)
{
if (workSheet.Name.Trim() == "Sample")
{
workSheet.Cells["C" + rowIndex].Value = "15.05.2017";
workSheet.Cells["D" + rowIndex].Value = 21701503;
workSheet.Cells["E" + rowIndex].Value = "21701503109W";
workSheet.Cells["F" + rowIndex].Value = 304;
workSheet.Cells["G" + rowIndex].Value = 200;
workSheet.Cells["H" + rowIndex].Value = 1520;
workSheet.Cells["I" + rowIndex].Value = 11350;
workSheet.Cells["J" + rowIndex].Formula = "=7.85*G1701*H1701*I1701/1000000000";
workSheet.Cells["K" + rowIndex].Value = 27.080;
excelPackage.Save();
break;
}
}
}
}
catch (Exception ex)
{
throw ex;
}
}
private int ReadCountFromProdReport(string fileName)
{
try
{
string logDirectory = System.Configuration.ConfigurationManager.AppSettings["LogDirectory"].ToString().Trim();
string filePath = logDirectory + fileName + ConfigurationManager.AppSettings["ExcelSaveFileExtension"].ToString().Trim();
using (ExcelPackage excelPackage = new ExcelPackage(new FileInfo(filePath)))
{
object count = null;
foreach (ExcelWorksheet workSheet in excelPackage.Workbook.Worksheets)
{
if (workSheet.Name.Trim() == "Report")
{
count = workSheet.Cells["E23"].Value;
break;
}
}
return Convert.ToInt32(count);
}
}
catch (Exception ex)
{
throw ex;
}
}

This command requires at least two rows of source data

I am getting this error:
This command requires at least two rows of source data. You cannot use the command on a selection in only one row. Try the following:
- If you're using an advanced filter, select a range of cells that contains at least two rows of data. Then click the Advanced Filter command again.
- I you're creating a PivotTable, type a cell reference or select a range that includes at least two rows of data
intermittently on this line of code:
xlWorkBook.RefreshAll();
There are two worksheets. One has a pivot table and one has raw data. Sometimes there is only one row of data. For multiple rows of data the line of code above always works; however, for only 1 row of data, the code above sometimes works, and sometimes I get the error message above.
In addition to this, the worksheet containing the pivot table is not refreshed; however, if I re-open the file, it also does not refresh, unless I explicitly refresh it manually.
What is going on here? Why am I getting this error only sometimes?
Thank you so much for your guidance.
if at all helpful, i am including the entire method:
private void SortandCreateFile(string column, string email, string emailStartPos) {
string replacetext = "";
try {
var valueRange = xlWorkSheet.get_Range(column + emailStartPos, column + range.Rows.Count.ToString());
var deleteRange = valueRange;
xlApp.Visible = false;
int startpos = 0;
int endPos=0;
bool foundStart = false;
Excel.Range rng = xlWorkSheet.get_Range(column + "1", column + range.Rows.Count.ToString());
string tempstring = "d";
int INTemailStartPos = Convert.ToInt16(emailStartPos);
for (int rCnt = INTemailStartPos; rCnt <= rng.Count; rCnt++) {
Excel.Range cell = (Excel.Range)rng[rCnt, 1];
try {
if (cell.Value2 != null)
tempstring = cell.Value2.ToString();
else {
startpos = rCnt;
releaseObject(cell); /////////
break;
}
}
catch (Exception ee)
{
MessageBox.Show(ee.ToString());
}
//grab the text from column link texdtbox
Excel.Range rngLinkColumn;
Excel.Range replacetextcell=null;
if (FormControls.ColumnLink.Length > 0) {
rngLinkColumn = xlWorkSheet.get_Range(FormControls.ColumnLink + "1", FormControls.ColumnLink + range.Rows.Count.ToString());
replacetextcell = (Excel.Range)rngLinkColumn[rCnt, 1];
}
//locate email
if (cell.Value2.ToString() == email ) {
//we found the starting position of the email we want!
//this will tell us which row of data to start from
startpos = rCnt;
if (FormControls.ColumnLink.Length > 0)
replacetext = replacetextcell.Value2.ToString();
releaseObject(cell); /////////
break;
}
releaseObject(cell);
}
int foundstartminusONE = startpos - 1;
int rngcount = rng.Count + INTemailStartPos;
//delete everything from the top UNTIL the row of the email address that we need
if (startpos != INTemailStartPos) {
deleteRange = xlWorkSheet.get_Range(column + INTemailStartPos.ToString() + ":" + "CF" + foundstartminusONE.ToString(), Type.Missing);
deleteRange = deleteRange.EntireRow;
deleteRange.Delete(Excel.XlDeleteShiftDirection.xlShiftUp);
}
for (int rCnt = INTemailStartPos; rCnt <= rng.Count; rCnt++) {
Excel.Range cell = (Excel.Range)rng[rCnt, 1];
try {
if (cell.Value2 != null )
tempstring = cell.Value2.ToString();
else {
endPos = rCnt - 1;
releaseObject(cell);////////
break;
}
}
catch (Exception ee) {
//MessageBox.Show(ee.ToString());
}
//locate email
if (cell.Value2.ToString() != email ) {
//we found where the last email address is that we need
//this is where the issue is occurring i think with the deleting the last row
endPos = rCnt;
releaseObject(cell);////////
break;
}
releaseObject(cell);
}
//delete all the stuff AFTER the email address that we need
if (endPos != 0) {
deleteRange = xlWorkSheet.get_Range(column + endPos + ":" + "CF" + rngcount.ToString(), Type.Missing);
deleteRange = deleteRange.EntireRow;
deleteRange.Delete(Excel.XlDeleteShiftDirection.xlShiftUp);
}
//when the user opens the excel file, we want the focus to be here
var rangehome = xlWorkSheet.get_Range(FormControls.FocusOn, FormControls.FocusOn);
xlWorkSheet.Activate();
rangehome.Select();
string filename = xlWorkBook.Path + #"\" + email + ".xlsx";
string fileSubstring = filename.Substring(0, filename.IndexOf(".xlsx"));
string randomfileString = Guid.NewGuid().ToString("N").Substring(0, 10) + ".xlsx";
string targetfilenameRename = fileSubstring + randomfileString;
//((Excel.Worksheet)this.Application.ActiveWorkbook.Sheets[FormControls.WorksheetFocus]).Activate();
//((Excel.Worksheet)Excel.Application.ActiveWorkbook.Sheets[1]).Activate();
Excel.Worksheet xlWorkSheetFocus = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(FormControls.WorksheetFocus);
xlWorkSheetFocus.Activate();
xlWorkBook.SaveAs(targetfilenameRename, Excel.XlFileFormat.xlWorkbookDefault, Type.Missing, Type.Missing,
false, false, Excel.XlSaveAsAccessMode.xlNoChange,
Type.Missing, Type.Missing, Excel.XlSaveConflictResolution.xlLocalSessionChanges, Type.Missing, Type.Missing);
try {
xlWorkBook.RefreshAll();
}
catch { }
xlWorkBook.Save();
string targetfile = xlWorkBook.Path + #"\" + FormControls.FileName + " - "
+ email.Substring(0, email.IndexOf("#")) + ".xlsx";
System.IO.File.Copy(targetfilenameRename, targetfile, true);
string body = FormControls.eMailBody;
body = body.Replace("%replacetext%", replacetext);
//replace %replacetext% in body
string targetfileSubstring = targetfile.Substring(0, targetfile.IndexOf(".xlsx"));
string randomString = Guid.NewGuid().ToString("N").Substring(0, 10)+".xlsx";
string targetfileRename = targetfileSubstring+randomString;
while (true) {
try {
SendEmail(targetfile, email, FormControls.eMailSubject, body,FormControls.eMailFrom);
}
catch (Exception ee) {
MessageBox.Show(ee.ToString());
continue;
}
// all is good
break;
}
releaseObject(valueRange);
releaseObject(deleteRange);
File.Copy(targetfile, targetfileRename, true);
}
catch (Exception e) {
MessageBox.Show(e.ToString());
}
finally {
//DisposeMe();
// Release all COM RCWs.
// The "releaseObject" will just "do nothing" if null is passed,
// so no need to check to find out which need to be released.
// The "finally" is run in all cases, even if there was an exception
// in the "try".
// Note: passing "by ref" so afterwords "xlWorkSheet" will
// evaluate to null. See "releaseObject".
releaseObject(range);
releaseObject(xlWorkSheet);
releaseObject(xlWorkBook);
// The Quit is done in the finally because we always
// want to quit. It is no different than releasing RCWs.
if (xlApp != null) {
xlApp.Quit();
}
releaseObject(xlApp);
}
}

The only way I could replicate this error with a pivot table was by attempting to create one off a range that didn't have column headers, just like on the screenshot from Stephan1010's answer.
In the GetPivotData Excel function, pivot fields are referred to by their names (=GETPIVOTDATA("EmailAddress",$A$3)); thus, it makes sense to disallow a data source that wouldn't have them.
The solution would be to pivot over a ListObject instead of a Range - in Excel when you select, say, range $A$1:$C$1 and format as table (from the Ribbon), the table that results will span $A$1:$C$2; the contents of the first row becomes the column headers and the second row is a valid, empty record. Interesting to note that this happens (the 2-row span) regardless of whether or not you check the "My table has headers" checkbox (the data will be moved to the first row and the table will contain default "Column1"-"Column2"-"Column3" headers if the checkbox is cleared).
In other words, a ListObject is always a valid data source for a pivot table, while a Range may not contain enough rows. Also if you don't have column headers and you create a pivot table with range $A$1:$C$2, the record at $A$1:$C$1 will be used as column headers, which means that first record is lost.
From the code you have supplied I would presume the pivot table is already present and connected to some [named?] range in a template workbook that contains the macro. Turning your range into a table might be as trivial as selecting format as table from the Ribbon. And then you could have code like this to remove all unnecessary rows while still keeping a valid data source for the pivot table:
public void DeleteExtraTableRows(string emailAddress, Excel.ListObject table)
{
try
{
var rowIndex = 0;
var wasDeleted = false;
while (rowIndex <= table.ListRows.Count)
{
if (!wasDeleted) rowIndex++;
var row = table.ListRows[rowIndex];
var range = (Excel.Range)row.Range.Cells[1, 1];
var value = range.Value2;
if (value != null && !string.Equals(emailAddress, value.ToString()))
{
row.Delete();
wasDeleted = true;
}
}
}
catch (Exception e)
{
MessageBox.Show(e.Message + "\n\n" + e.StackTrace);
}
}
There is also a possibility that the email is never found in the loop's if (cell.Value2.ToString() == email ) condition, which would end up deleting all rows from your range - even if the only difference is an extra space at the end of the in-cell value. With the above code, even if all email addresses get deleted the data source remains a valid one for a pivot table that would be connected to it.
EDIT:
In Excel you turn a Range into a ListObject by selecting the range in question and clicking the Format as table Ribbon button, from the Home tab. Alternatively you can create one like this:
var range = ((Excel.Range)(worksheet.Range[worksheet.Cells[1, 1], worksheet.Cells[3, 1]]));
var table = worksheet.ListObjects.Add(SourceType: Excel.XlListObjectSourceType.xlSrcRange, Source: range,
XlListObjectHasHeaders: Excel.XlYesNoGuess.xlYes);
table.TableStyle = "TableStyleMedium3";
In code, you can access all ListObjects on a worksheet using the ListObjects property:
var worksheet = (Excel.Worksheet) Globals.ThisAddIn.Application.ActiveSheet;
var tables = worksheet.ListObjects;
Then, you can access a specific ListObject /table with several different ways:
var myTable = tables[1];
var myTable = tables.Item["Table1"];
var myTable = tables.OfType<Excel.ListObject>().FirstOrDefault(t => t.Name == "Table1");
As rows are added from the table, the actual range it refers to will be expanded accordingly; use myTable.Range to access the range in question.

i suppose this situation occurs because of the pivot tables you got.
cause refresh all will trigger pivot table's refresh command too.
look at the code below. It may give you an idea about it. Its not about 1 row im sure. i checked it everthing works just fine its most posibly caused by pivot tables.
Microsoft.Office.Interop.Excel.Application xlApp = new Microsoft.Office.Interop.Excel.Application();
Microsoft.Office.Interop.Excel.Workbook xlWorkbook = xlApp.Workbooks.Open("some.xlsx");
// For each worksheet we got
foreach (Microsoft.Office.Interop.Excel.Worksheet worksheet in xlWorkbook.Sheets)
{ // and each pivot table in each worksheet
foreach (Microsoft.Office.Interop.Excel.PivotTable pivot in worksheet.PivotTables())
{ // disable BackgroundQuery
pivot.PivotTableWizard(BackgroundQuery: false);
}
}
// try to refresh all sheet
try { xlWorkbook.RefreshAll(); } catch { }
// then save
xlWorkbook.Save();

The obvious answer seems to be that sometimes you have one row of data as the source for your pivot table and sometimes you don't - even when you think you still do. I have not been able to create a pivot table(or change the source of a pivot table) to one row of data:
but if you are able to somehow figure out a way to do this then you have found your answer. There is no reason you can't have one row of data as your source just from a practical/theoretical perspective, but it looks like excel tries to prevent that from happening(maybe because the code assumes two rows). So if you do find a way, then it is probably a bug. Good Luck.

Outlook returns error: The messaging interface has returned an unknown error

I am having some problems with a piece of code, I am trying to import data from a source (at this time an access database) into a custom form but i keep getting the above error.
When i use a VBscript inside the source database all contacts import correctly.
When i repair the PST it still gives this error.
When i add a delay of 450 ms. the error also occurs but later on in the process.
Having Outlook opened or closed does not matter.
I am using the following method
string[] arrFolders = strFolders.Split('\\');
Outlook.Application app = null;
Outlook.MAPIFolder folder = null;
try {
app = new Outlook.Application();
folder = app.GetNamespace("MAPI").Folders[arrFolders[0]];
} catch (Exception ex) {
writeLogLine("Error creating Outlook instance: " + ex.Message);
MessageBox.Show("Error creating Outlook instance\r\n" + ex.Message);
intErrorCount++;
blnHasErrors = true;
blnAbort = true;
}
try {
for (int i = 1; i < arrFolders.Length; i++) {
folder = folder.Folders[arrFolders[i]];
}
} catch (Exception ex) {
writeLogLine("Error navigating to DRM folder: " + ex.Message);
MessageBox.Show("Error navigating to DRM folder\r\n" + ex.Message);
intErrorCount++;
blnHasErrors = true;
blnAbort = true;
}
setProgressbarMaximum(dtResults.Rows.Count);
setProgressbarMode(ProgressBarStyle.Continuous);
//int intRowCount = 0;
foreach (DataRow drItem in dtResults.Rows) {
if (strDRMType == "Contact") {
try {
Outlook.ContactItem x = (Outlook.ContactItem)folder.Items.Add("IPM.Contact." + strFormName);
for (int i = 0; i < arrMappings.GetLength(0); i++) {
if (arrMappings[i, 1] != null && drItem[arrMappings[i, 0]].ToString() != "") {
x.UserProperties[arrMappings[i, 1]].Value = drItem[arrMappings[i, 0]].ToString();
}
}
x.Save();
} catch (Exception ex) {
writeLogLine("Error importing contact: " + ex.Message);
intErrorCount++;
blnHasErrors = true;
}
}
as i said, when i loop the code it will throw exceptions after 100 to 200 contacts, when i add a delay it will get to contact 400/500 before failing.
This code is supposed to be for a generic import tool for this specific form so there is no need for hardcoding the source column names to the form fields in the import code.
Any help is appreciated.

I'm assuming this is not an Outlook add-in, since you say it doesn't matter if OL is open or closed, right?
One thing you may want to do is ensure you are releasing the COM objects once you are done with them, using System.Runtime.InteropServices.Marshal.ReleaseComObject(...). Also, when you use dot notation like "namespace.Folders[..].Name" you are actually leaking a reference to both the Folders collection object and a Folder object.
When you do folders.Items.Add(...) inside a loop, that leaks a lot of objects.
So, clean up your COM references first, and see how that affects your situation.
Here's how I typically use COM objects:
MyComLib.Foo foo = null;
try
{
foo = new MyComLib.Foo();
foo.DoSomething();
} catch(COMException exc)
{
// handle error, or rethrow
}
finally
{
if(foo != null)
Marshal.ReleaseComObject(foo);
}