This morning i have worked with EPPlus in my application MVC 3.
using (ExcelPackage pck = new ExcelPackage(fileInfoNew,fileInfoTemplate))
{ pck.Save(); }
When the file generated is saved and opened, i got this error:
"unreadable content", around "xl/styles.xml".
After some time,I have tested by app with the blank .xlsx file.. and I have the same result!
Google helped me: Epplus 3.1.2 has bug! Now, with the version 3.1.1, my app worked!