Excel “External table is not in the expected forma

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 Excel. In other words, I have to open the file in Excel first before I can read if from my C# program. The xlsx file is on a share on our network. How can I read the file without having to open it first? Thanks

string sql = "SELECT * FROM [Sheet1$]";
string excelConnection = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + pathname + ";Extended Properties=\"Excel 8.0;HDR=YES;IMEX=1;\"";

using (OleDbDataAdapter adaptor = new OleDbDataAdapter(sql, excelConnection)) {
    DataSet ds = new DataSet();
    adaptor.Fill(ds);
}

Answer 1

Just add my case. My xls file was created by a data export function from a website, the file extention is xls, it can be normally opened by MS Excel 2003. But both Microsoft.Jet.OLEDB.4.0 and Microsoft.ACE.OLEDB.12.0 got an "External table is not in the expected format" exception.

Finally, the problem is, just as the exception said, "it's not in the expected format". Though it's extention name is xls, but when I open it with a text editor, it is actually a well-formed html file, all data are in a <table>, each <tr> is a row and each <td> is a cell. Then I think I can parse it in a html way.

Answer 2

That excel file address may have an incorrect extension. You can change the extension from xls to xlsx or vice versa and try again.

Answer 3

Just adding my solution to this issue. I was uploading a .xlsx file to the webserver, then reading from it and bulk inserting to SQL Server. Was getting this same error message, tried all the suggested answers but none worked. Eventually I saved the file as excel 97-2003 (.xls) which worked... only issue I have now is that the original file had 110,000+ rows.

Answer 4

Thanks for this code :) I really appreciate it. Works for me.

public static string connStr = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + path + ";Extended Properties=Excel 12.0;";

So if you have diff version of Excel file, get the file name, if its extension is .xlsx, use this:

Private Const connstring As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + path + ";Extended Properties=Excel 12.0;";

and if it is .xls, use:

Private Const connstring As String = "Provider=Microsoft.Jet.OLEDB.4.0;" & "Data Source=" + path + ";Extended Properties=""Excel 8.0;HDR=YES;"""

Answer 5

the file might be locked by another process, you need to copy it then load it as it says in this post

Answer 6

I recently saw this error in a context that didn't match any of the previously listed answers. It turned out to be a conflict with AutoVer. Workaround: temporarily disable AutoVer.