Created Unassigned: Unable to edit existing comments in excel. [15030]

Unable to edit existing comments in excel.
In my excel when I am trying to update existing comments (code provided below) .when I try to open the excel I get following message “Excel found unreadable content in ‘test.xlsx’. Do you want to recover the contents of this workbook? If you trust the source of this workbook, click yes.”
In the excel all the comments in the workbook are lost.
using (newPack = new ExcelPackage(fileInfo))
{
var wkBk = newPack.Workbook.Worksheets["Company"];
var wkBk2 = newPack.Workbook.Worksheets["Summary"];
var cell= wkBk.Cells["A6"];
if (cell.Comment != null)
{
cell.Comment.Text = "Hello edited comments";
}
newPack.Save();
}