Adding pivot table results in corrupt xlsx when constructing ExcelPackage with existing office 2016 file

[JasperE84]

Hi there,
I noticed EPPlus creates corrupt excel files when starting from an existing Excel template.

Steps to reproduce

• Install latest office 365 (office 2016)

• I am using: 1705 (Build 8201.2193 CLick-to-Run) / Deferred Channel

• Create folder c:\temp

• Right click in windows explorer in c:\temp empty space, New file -> Microsoft Excel file

• Name file "template.xlsx"
  Here is the blank file I then get:
  template.xlsx

• Modify Sample12.cs as following:

string fileInput = @"c:\temp\template.xlsx";
string fileOutput = @"c:\temp\output.xlsx";
File.Copy(fileInput, fileOutput);
FileInfo newFile = new FileInfo(fileOutput);
using (ExcelPackage pck = new ExcelPackage(newFile))
{
<snip>
pck.Save();
}
return fileOutput;

• Run sample application

• Try to open c:\temp\output.xlsx

• Excel will say file is corrupted
  Here is the corrupt file I'm getting
  output.xlsx

Workaround:

• Take Sample12.xlsx from the default sample app without modifications
• Copy the worksheets from your Excel 2016 template to the Sample12.xlsx file
• Save using Excel
• Use that as your new template

[JanKallman]

This is fixed in 4.5.1