External table is not in the expected format.

"External table is not in the expected format." typically occurs when trying to use an Excel 2007 file with a connection string that uses: Microsoft.Jet.OLEDB.4.0 and Extended Properties=Excel 8.0

Using the following connection string seems to fix most problems.

public static string path = @"C:\src\RedirectApplication\RedirectApplication\301s.xlsx";
public static string connStr = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + path + ";Extended Properties=Excel 12.0;HDR=Yes;IMEX=1;";