Got error: file format or file extension is not valid. Verify that the file has been corrupted and that file extension matches the format of the file

May 11, 2015 at 9:59 PM
DotNetNuke.Services.Exceptions.ModuleLoadException: Package object was closed and disposed, so cannot carry out operations on this object or any stream opened on a part of this package.

System.ObjectDisposedException: Package object was closed and disposed, so cannot carry out operations on this object or any stream opened on a part of this package.
at System.IO.Packaging.Package.PartExists(Uri partUri)
at OfficeOpenXml.ExcelWorkbook.Save()
at OfficeOpenXml.ExcelPackage.GetAsByteArray(Boolean save)


Any advise?