OLEDBConnection.Open() generates 'Unspecified error'

Question

I have an application that uploads an Excel .xls file to the file system, opens the file with an oledbconnection object using the .open() method on the object instance and then stores the data in a database. The upload and writing of the file to the file system works fine but I get an error when trying to open the file on our production server only. The application works fine on two other servers (development and testing servers).

The following code generates an 'Unspecified Error' in the Exception.Message.

Quote:

        System.Data.OleDb.OleDbConnection x = new System.Data.OleDb.OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + location + ";Extended Properties='Excel 8.0;HDR=Yes;IMEX=1'");
        try
        {
            x.Open();
        }
        catch (Exception exp)
        {
            string errorEmailBody = " OpenExcelSpreadSheet() in Utilities.cs.  " + exp.Message;
            Utilities.SendErrorEmail(errorEmailBody);
        }

:End Quote

The server's c:\\temp and c:\Documents and Settings\\aspnet\local settings\temp folder both give \aspnet full control.

I believe that there is some kind of permissions issue but can't seem to find any difference between the permissions on the noted folders and the folder/directory where the Excel file is uploaded. The same location is used to save the file and open it and the methods do work on my workstation and two web servers. Windows 2000 SP4 servers.

Answer 1

While the permissions issue may be more common you can also encounter this error from Windows file system/Access Jet DB Engine connection limits, 64/255 I think. If you bust the 255 Access read/write concurrent connections or the 64(?) connection limit per process you can get this exact same error. At least I've come across that in an application where connections were being continually created and never properly closed. A simple Conn.close(); dropped in and life was good. I imagine Excel could have similar issues.

Answer 2

If you're using impersonation you'll need to give permission to the impersonation user instead of/in addition to the aspnet user.

Answer 3

Anything in the inner exception? Is this a 64-bit application? The OLEDB providers don't work in 64-bit. You have to have your application target x86. Found this when getting an error trying to open access DB on my 64-bit computer.

Answer 4

Yup. I did that too. Took out IMEX=1, took out Extended Properties, etc. I managed to break it on the dev and test servers. :) I put those back in one at a time until it was fixed on dev and test again but still no workie on prod.

Answer 5

Try wrapping the location in single quotes

System.Data.OleDb.OleDbConnection x = new System.Data.OleDb.OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source='" + location + "';Extended Properties='Excel 8.0;HDR=Yes;IMEX=1'");

Answer 6

I've gotten that error over the permissions thing, but it looks like you have that covered. I also have seen it with one of the flags in the connection string -- you might play with that a bit.