Excel “External table is not in the expected format.”

Question

I\'m trying to read an Excel (xlsx) file using the code shown below. I get an \"External table is not in the expected format.\" error unless I have the file already open in

Answer 1

Working with some older code and came across this same generic exception. Very hard to track down the issue, so I thought I'd add here in case it helps someone else.

In my case, there was code elsewhere in the project that was opening a StreamReader on the Excel file before the OleDbConnection tried to Open the file (this was done in a base class).

So basically I just needed to call Close() on the StreamReader object first, then I could open the OleDb Connection successfully. It had nothing to do with the Excel file itself, or with the OleDbConnection string (which is naturally where I was looking at first).