Excel: can only open file if using absolute path, why?

Question

I have some trouble to understande why I´m getting an exception. I have something like this:

string path = \"file.xls\";
if (File.Exists(path))
{
  Excel.App         


        

Answer 1

This happens because there are two processes involved, each of which has their own Current Working Directory (CWD).

Your process (the one calling File.Exists()) has a CWD which happens to hold the file that you're using. Excel has a different CWD (probably the location of the Excel executable) which of course doesn't hold the file.

You can fix this by using:

path = System.IO.Path.GetFullPath(path);

before passing path to Workbooks.open(path)

It might be possible to change Excel's CWD by calling a macro using ExecuteExcel4Macro.

See here for some details: Set Current Directory in Excel.Application via .NET Office PIA