InnerException when saving package with EPPLUS - Unauthorized Access

Question

I'm trying to create an Excel file using EPPLUS in a controller of an MVC application.

The file appears to be getting created just fine, but chokes when I try to save:

[HttpPost]
public FileResult getBill(int billMonth, int billYear)
{
    FileInfo newFile = new FileInfo("C:\\cool.xlsx");
    if (newFile.Exists)
    {
        newFile.Delete();  // ensures we create a new workbook
        newFile = new FileInfo("cool.xlsx");
    }
    using (ExcelPackage package = new ExcelPackage(newFile))
    {
        // add a new worksheet to the empty workbook
        ExcelWorksheet worksheet = package.Workbook.Worksheets.Add("Inventory");
        //Add the headers
        worksheet.Cells[1, 1].Value = "ID";    

        ...

        // save our new workbook and we are done!
        package.Save();
    }

The error I am getting: Error saving file C:\cool.xlsx

 System.InvalidOperationException was unhandled by user code
  HResult=-2146233079
  Message=Error saving file C:\cool.xlsx
  Source=EPPlus
  StackTrace:
       at OfficeOpenXml.ExcelPackage.Save()
       at ...BillingController.getBill(Int32 billMonth, Int32 billYear) in ...\Controllers\BillingController.cs:line 118
       at lambda_method(Closure , ControllerBase , Object[] )
       at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
       at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass37.<>c__DisplayClass39.<BeginInvokeActionMethodWithFilters>b__33()
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49()
  InnerException: System.UnauthorizedAccessException
       HResult=-2147024891
       Message=Access to the path 'C:\cool.xlsx' is denied.
       Source=mscorlib
       StackTrace:
            at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
            at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
            at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy)
            at System.IO.FileStream..ctor(String path, FileMode mode)
            at OfficeOpenXml.ExcelPackage.Save()
       InnerException: 

Ultimately, I don't really want to even save this, I just want to return it as a FileResult to user, but figured this was a necessary step in getting it setup.

Answer 1

The System.UnauthorizedAccessException is a clear indicator that this is a permissions issue. You are saving to a directory that you don't have permission to write to.

Try saving to some subfolder, instead of directly to the C: drive. If the application is running out of IIS, give permissions on the folder to your application pool.