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Saving an ExcelPackage with exclusive lock of excel, giving error after opening excel file - C# - EPPlus

My objective is to write some data into an excel.
Here i am opening a file with file stream by exclusive lock (FileMode.Open, FileShare.Read etc., I need to lock the file to restrict others writing into excel while i am processing.) then writing some content into it and finally close the stream, so that other threads can write into this file. I am using EPPlus(5.7.4) version.
The code i am using here is :
public void WriteToExcel()
{
using (var stream = new FileStream(path, FileMode.Open, FileAccess.ReadWrite, FileShare.Read))
using (var excelPackage = new ExcelPackage(stream))
{
DoSomething(excelPackage);
excelPackage.SaveAs(stream);
stream.Close();
}
}
public void DoSomething(ExcelPackage excelPackage)
{
var cell = excelPackage.Workbook.Worksheets[0].Cells[2, 3];
cell.Value = "some value";
}
I put a break point in using statement and opened excel in the middle of execution and it showing a message saying like below which is correct.
But once i finish with execution when i try to open excel file it showing below error message.
We found a problem with some content in Sample.xlsx. Do you want us to try to recover as much as we can? if you trust the source of this book, Click Yes
I tried in different ways but none worked for me, as same error message is displaying. Can someone help me resolving this issue.

The problem is that you're reading from and rewriting to the same file stream simultaneously.
You can test this by changing excelPackage.SaveAs(new FileInfo("Book2.xlsx")); and create a new file - your file will be created without any issues.
You could open your original document, write the changes to a new file, then delete the original file and rename the new file back to the original name:
ExcelPackage.LicenseContext = LicenseContext.NonCommercial;
using (var stream = new FileStream("Book1.xlsx", FileMode.Open, FileAccess.ReadWrite, FileShare.Read))
using (var excelPackage = new ExcelPackage(stream))
{
DoSomething(excelPackage);
excelPackage.SaveAs(new FileInfo("Book2.xlsx"));
}
File.Delete("Book1.xlsx");
File.Move("Book2.xlsx", "Book1.xlsx");
The caveat with this is that if you have multiple things trying to access that file, then they might throw FileNotFound exceptions if they happen to try to open Book1.xlsx after it's delete and before Book2.xlsx is renamed.
That said, if you're dealing with that level of parallelism then you shouldn't be using a Excel file.
Side note: You don't need stream.Close(); as the using block automatically closes the stream.

Below code useful to me, you can refer it.
public void WriteToExcel()
{
string path = #"C:\Use**op\aa.xlsx";
FileInfo file = new FileInfo(path);
ExcelPackage.LicenseContext = LicenseContext.NonCommercial;
using (ExcelPackage package = new ExcelPackage(file))
{
DoSomething(package);
}
}
public void DoSomething(ExcelPackage package)
{
ExcelWorksheet worksheet = package.Workbook.Worksheets[0];
worksheet.Cells[2,4].Value = "some value";
package.Save();
}

Converting a .xlsx file to .csv using Syncfusion.XlsIO - Null reference exception

I have a file in blob storage that is in .xslx format and I am trying to convert it to .csv format using Syncfusion.XlsIO Nuget package.
I have tried the following:
private async Task ConvertExcelToCsv()
{
var fileName = await _fileStore.GetContainerFileAsync(AppSettingsConstants.FileNames.Container, "myfile.xlsx");
using (ExcelEngine excelEngine = new ExcelEngine())
{
var application = excelEngine.Excel;
var workbook = application.Workbooks.Open(fileName.Name);
var worksheet = workbook.Worksheets[1];
worksheet.SaveAs("myfile.csv", ",");
}
}
When I debug, the fileName is retrieved successfully, but the application breaks on using (ExcelEngine excelEngine = new ExcelEngine()) with a NullReferenceException error.
Where am I going wrong here?

The way you can do it is defined here: https://www.syncfusion.com/kb/9098/how-to-export-excel-data-to-csv-file
Most likely, you would need to install from NuGet not only Syncfusion.XlsIO.WinForms , but also System.Drawing.Common and System.Security.Permissions.
This code worked:
try
{
//Initialize ExcelEngine
using (ExcelEngine excelEngine = new ExcelEngine())
{
//Initialize Application
IApplication application = excelEngine.Excel;
//Set default version for application
application.DefaultVersion = ExcelVersion.Excel2013;
//Open a workbook to be export as CSV
IWorkbook workbook = application.Workbooks.Open(#"E:\Users\Public\Documents\" + "ExcelFile.xlsx");
//Accessing first worksheet in the workbook
IWorksheet worksheet = workbook.Worksheets[0];
//Save the workbook to csv format
worksheet.SaveAs("Output.csv", ",");
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
throw;
}
Make sure you have permission to access the Excel file. Usually, it helps if you test it with files which are saved on another drive than on which Windows is installed (e.g. E:\, if Windows is on C:\).

Thank you, it turned out I was missing a reference to System.Drawing nuget

Removing vbaProject.bin in XML not enough to save as xlsx

After exporting data into an Excel workbook with macros (xlsm), I run the macro and then remove the macro in order to be able to save the workbook as xlsx. For removing macros, I open the xlsm as zip archive (via C# ZipFile class), remove the entry "xl/vbaProject.bin" and remove a relation within "xl/_rels/workbook.xml.rels". Then I rename the file from xlsm to xlsx. That works fine so far but when I open the xlsx file in Excel, I get "Excel cannot open the file because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file", so there seems something to be missing in order to completely remove the vba code within the workbook. Can anyone help me here?
const string vbaProjectEntryName = "xl/vbaProject.bin"; // Contains the VBA code
const string relationsEntryName = "xl/_rels/workbook.xml.rels"; // Relation/Link to the vba project
using (var zip = ZipFile.Open(fileName, ZipArchiveMode.Update))
{
var entry = zip.GetEntry(vbaProjectEntryName);
if (entry != null)
{
entry.Delete();
entry = zip.GetEntry(relationsEntryName);
if (entry != null)
{
var contents = string.Empty;
using (var streamReader = new StreamReader(entry.Open()))
{
contents = streamReader.ReadToEnd();
}
var relationText = "<Relationship Id=\"rId6\" Type=\"http://schemas.microsoft.com/office/2006/relationships/vbaProject\" Target=\"vbaProject.bin\"/>";
contents = contents.Replace(relationText, string.Empty);
entry.Delete();
entry = zip.CreateEntry(relationsEntryName);
using (var streamWriter = new StreamWriter(entry.Open()))
{
streamWriter.Write(contents);
}
}
}
}

Problematic corruption of .xlsx files with NPOI - Excel cannot open the file 'file.xlsx" because the file format or file extension is not valid

When reading or modifying some user-created .xlsx files, I get the following error message:
We found a problem with some content in 'test.xlsx'. Do you want us to try to recover as much as we can? If you trust the source of this workbook, click Yes.
Clicking Yes gets me another message:
Excel cannot open the file 'test.xlsx' because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file.
Example of a problem .xlsx file here (before put in NPOI).
Here's the same file, now corrupted after being read from and written back with iWorkbook.Write(filestream); here.
I have no issues creating a new .xlsx file with the following code:
string newPath = #"C:\MyPath\test.xlsx";
using (FileStream fs = new FileStream(newPath, FileMode.Create, FileAccess.Write))
{
IWorkbook wb = new XSSFWorkbook();
wb.CreateSheet();
ISheet s = wb.GetSheetAt(0);
IRow r = s.CreateRow(0);
r.CreateCell(0);
ICell c = r.GetCell(0);
c.SetCellValue("test");
wb.Write(fs);
fs.Close();
}
That works fine.
Even opening one of the problem child .xlsx files, setting it to an IWorkbook and writing it back to the file works:
string newPath = #"C:\MyPath\test.xlsx";
using (FileStream fs = new FileStream(newPath, FileMode.Open, FileAccess.ReadWrite))
{
IWorkbook wb = new XSSFWorkbook(fs);
wb.Write(fs);
fs.Close();
}
However, after running through code that reads from it, gets ISheets, IRows, ICells, etc.... it corrupts the .xlsx file. Even though I specifically removed anything that modifies the workbook. No Creates, Sets, Styles, etc. with NPOI.
I can't really include my code because it would just be confusing, but for the sake of completeness I'm really only using the following types and functions from NPOI during this test:
IWorkbook
XSSFWorkbook
ISheet
IRow
ICell
.GetSheetAt
.GetRow
.GetCell
.LastRowNum
So one of those causes corruption. I would like to eventually set values again and get it working like I have for .xls.
Has anyone experienced this? What are some NPOI functions that could cause corruption? Any input would be appreciated.
Edit: Using NPOI v2.2.1.

I think the problem is that you are reading from, and writing to, the same FileStream. You should be doing the read and write using separate streams.
Try it like this:
string newPath = #"C:\MyPath\test.xlsx";
// read the workbook
IWorkbook wb;
using (FileStream fs = new FileStream(newPath, FileMode.Open, FileAccess.Read))
{
wb = new XSSFWorkbook(fs);
}
// make changes
ISheet s = wb.GetSheetAt(0);
IRow r = s.GetRow(0) ?? s.CreateRow(0);
ICell c = r.GetCell(1) ?? r.CreateCell(1);
c.SetCellValue("test2");
// overwrite the workbook using a new stream
using (FileStream fs = new FileStream(newPath, FileMode.Create, FileAccess.Write))
{
wb.Write(fs);
}

I had the same problem. In my case the problem was not with the NPOI itself but with its dependency, SharpZipLib.
I used NPOI 2.3.0 and SharpZipLib 1.0.0. and it was given the the same error as in your case. The generated Excel was 0 bytes in size.
I downgraded the SharpZipLib back to 0.86.0 in the project where I was using the NPOI (a Service layer) and also in the MVC project(I had the package of SharpZipLib here too).
I also removed manually in web.config the assembly dependency previously created for SharpZipLib:
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
.......
<dependentAssembly>
<assemblyIdentity name="ICSharpCode.SharpZipLib" publicKeyToken="1b03e6acf1164f73" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-1.0.0.999" newVersion="1.0.0.999" />
</dependentAssembly>
</assemblyBinding>
I hope this helps someone.

I had the same error attempting to write the excel file to a memory stream and then downloading through my .net Core controller.
This code was my problem (At this point, workbook contained the NPOI excel file I created):
var fileName = $"export.xlsx";
var mimeType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
MemoryStream stream = new();
workbook.Write(stream);
byte[] output = stream.GetBuffer();
return File(output, mimeType, fileName);
The issue was this line:
byte[] output = stream.GetBuffer();
That line gave me a byte array that contained the contents of my excel file, but I did not realize that the GetBuffer returned not only the byte array representing the excel file, but also the remaining allocated memory for the byte array.
I replaced that line with this:
byte[] output = stream.ToArray();
and life was good.

When writing back to the file, be sure to use Create as FileMode method. If you use Open, the file will be corrupted because it will concatenate the new file at the end of the old one.
IWorkbook workbook;
using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
{
workbook = new XSSFWorkbook(file);
}
// do things to workbook...
using (FileStream file = new FileStream(filePath, FileMode.Create, FileAccess.Write))
{
workbook.Write(file);
}

Convert XLSM to XLSX

I'm using the EPPLUS library to read data from Excel to create another file. Unfortunately it does not support the .XLSM extension file. Is there a nice way to convert .XLSM files to .XLSX file for the purpose of reading the file with EPPLUS?
(using EPPLUS for reading would be nice because all my code is already written using it :) )

In order to do this you will need to use the Open XML SDK 2.0. Below is a snippet of code that worked for me when I tried it:
byte[] byteArray = File.ReadAllBytes("C:\\temp\\test.xlsm");
using (MemoryStream stream = new MemoryStream())
{
stream.Write(byteArray, 0, (int)byteArray.Length);
using (SpreadsheetDocument spreadsheetDoc = SpreadsheetDocument.Open(stream, true))
{
// Change from template type to workbook type
spreadsheetDoc.ChangeDocumentType(SpreadsheetDocumentType.Workbook);
}
File.WriteAllBytes("C:\\temp\\test.xlsx", stream.ToArray());
}
What this code does is it takes your macro enabled workbook file and opens it into a SpreadsheetDocument object. The type of this object is MacroEnabledWorkbook, but since you want it as a Workbook you call the ChangeDocumentType method to change it from a MacroEnabledWorkbook to a Workbook. This will work since the underlying XML is the same between a .xlsm and a .xlsx file.

Using the Open XML SDK, like in amurra's answer, but
in addition to changing doc type, VbaDataPart and VbaProjectPart should be removed, otherwise Excel will show error a file is corrupted.
using (var inputStream = File.OpenRead("C:\\temp\\test.xlsm"))
using (var outStream = new MemoryStream()) {
inputStream.CopyTo(outStream);
using (var doc = SpreadsheetDocument.Open(outStream, true)) {
doc.DeletePartsRecursivelyOfType<VbaDataPart>();
doc.DeletePartsRecursivelyOfType<VbaProjectPart>();
doc.ChangeDocumentType(DocumentFormat.OpenXml.SpreadsheetDocumentType.Workbook);
}
File.WriteAllBytes("C:\\temp\\test.xlsx", outStream.ToArray());
}

package xlsbtoxlsx;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.regex.Pattern;
import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.openxml4j.opc.PackagePart;
import org.apache.poi.openxml4j.opc.PackageRelationship;
import org.apache.poi.openxml4j.opc.PackageRelationshipCollection;
import org.apache.poi.ss.usermodel.WorkbookFactory;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbookType;
public class XlsbToXlsxConvertor {
public static void main(String[] args) throws Exception {
String inputpath="C:\\Excel Data Files\\XLSB\\CSD_TDR_20200823";
String outputpath="C:\\Excel Data Files\\XLSB\\output";
new XlsbToXlsxConvertor().xlsmToxlsxFileConvertor(inputpath, outputpath);
}
public void xlsmToxlsxFileConvertor(String inputpath, String outputpath) throws Exception {
XSSFWorkbook workbook;
FileOutputStream out;
System.out.println("inputpath " + inputpath);
File directoryPath = new File(inputpath);
// List of all files and directories
String contents[] = directoryPath.list();
System.out.println("List of files and directories in the specified directory:");
for (int i = 0; i < contents.length; i++) {
System.out.println(contents[i]);
// create workbook from XLSM template
workbook = (XSSFWorkbook) WorkbookFactory
.create(new FileInputStream(inputpath + File.separator + contents[i]));
// save copy as XLSX ----------------START
OPCPackage opcpackage = workbook.getPackage();
// get and remove the vbaProject.bin part from the package
PackagePart vbapart = opcpackage.getPartsByName(Pattern.compile("/xl/vbaProject.bin")).get(0);
opcpackage.removePart(vbapart);
// get and remove the relationship to the removed vbaProject.bin part from the
// package
PackagePart wbpart = workbook.getPackagePart();
PackageRelationshipCollection wbrelcollection = wbpart
.getRelationshipsByType("http://schemas.microsoft.com/office/2006/relationships/vbaProject");
for (PackageRelationship relship : wbrelcollection) {
wbpart.removeRelationship(relship.getId());
}
// set content type to XLSX
workbook.setWorkbookType(XSSFWorkbookType.XLSX);
// write out the XLSX
out = new FileOutputStream(outputpath + File.separator + contents[i].replace(".xlsm", "") + ".xlsx");
workbook.write(out);
out.close();
System.out.println("done");
workbook.close();
}
}
}