OpenXml SpreadsheetDocument SaveAs() produces corrupted document - why?

Question

This dead-simple code creates a file that Excel won't open.
How could this be failing?

using (SpreadsheetDocument doc = SpreadsheetDocument.Open(@"c:\dir\src.xlsx", true))
{
  doc.SaveAs(@"c:\dir\saved.xlsx");
}

Notes:

• Excel won't open saved.xlsx
• src.xlsx is known to exist and be valid (Excel opens it no problem)
• saved.xlsx is indeed produced, though it's about 500 bytes smaller than src.xlsx

Answer 1

If you meant this error: Stop debugging before opening the "saved.xlsx" file

I've checked. It works correctly: Output file