[c#] Excel "External table is not in the expected format."

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);
}

This can also be a file that contains images or charts, see this: http://kb.tableausoftware.com/articles/knowledgebase/resolving-error-external-table-is-not-in-expected-format

The recommendation is to save as Excel 2003

I was getting errors with third party and Oledb reading of a XLSX workbook. The issue appears to be a hidden worksheet that causes a error. Unhiding the worksheet enabled the workbook to import.

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).

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

I had the same problem. which as resolved using these steps:

1.) Click File

2.) Select "save as"

3.) Click on drop down (Save as type)

4.) Select Excel 97-2003 Workbook

5.) Click on Save button

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.

Ran into the same issue and found this thread. None of the suggestions above helped except for @Smith's comment to the accepted answer on Apr 17 '13.

The background of my issue is close enough to @zhiyazw's - basically trying to set an exported Excel file (SSRS in my case) as the data source in the dtsx package. All I did, after some tinkering around, was renaming the worksheet. It doesn't have to be lowercase as @Smith has suggested.

I suppose ACE OLEDB expects the Excel file to follow a certain XML structure but somehow Reporting Services is not aware of that.

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.

I have also seen this error when trying to use complex INDIRECT() formulas on the sheet that is being imported. I noticed this because this was the only difference between two workbooks where one was importing and the other wasn't. Both were 2007+ .XLSX files, and the 12.0 engine was installed.

I confirmed this was the issue by:

• Making a copy of the file (still had the issue, so it wasn't some save-as difference)
• Selecting all cells in the sheet with the Indirect formulas
• Pasting as Values only

and the error disappeared.

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;"""

If you still have this problem, then check your permissions, I tried many of these suggestions and my concrete problem was that the file that I wanted to process was under source control and the thread had no permissions, I had to change the entire folder permissions and it started to work (I was processing many files in there)... It also matches many suggestions like change the name of the file or check that the file is not loicked by another process.

I hope it helps you.

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

I recently had this "System.Data.OleDb.OleDbException (0x80004005): External table is not in the expected format." error occur. I was relying on Microsoft Access 2010 Runtime. Prior to the update that was automatically installed on my server on December 12th 2018 my C# code ran fine using Microsoft.ACE.OLEDB.12.0 provider. After the update from December 12th 2018 was installed I started to get the “External table is not in the expected format" in my log file.

I ditched the Microsoft Access 2010 Runtime and installed the Microsoft Access 2013 Runtime and my C# code started to work again with no "System.Data.OleDb.OleDbException (0x80004005): External table is not in the expected format." errors.

2013 version that fixed this error for me https://www.microsoft.com/en-us/download/confirmation.aspx?id=39358

2010 version that worked for me prior to the update that was automatically installed on my server on December 12th. https://www.microsoft.com/en-us/download/confirmation.aspx?id=10910 https://www.microsoft.com/en-us/download/confirmation.aspx?id=10910

I also had this error occur last month in an automated process. The C# code ran fine when I ran it debugging. I found that the service account running the code also needed permissions to the C:\Windows\Temp folder.

I had this problem and changing Extended Properties to HTML Import fixed it as per this post by Marcus Miris:

strCon = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & importedFilePathAndName _
         & ";Extended Properties=""HTML Import;HDR=No;IMEX=1"";"

My scope consists of template download and verifies the template when it's filled with data So,

1) Download a template (.xlsx) file with the header row. the file is generated using openxml and it's working perfectly.

2) Upload the same file without any change from it's downloaded state. This will cause a connection error and fails (OLEDB connection is using for reading the excel sheet).

Here if the data is filled the program works as expected.

Anybody having an idea the issue is connected with the file we are creating it's in xml format if we open it and just save convert it in to excel format and it works well.

Any idea to download the excel with the preferred file type?

This can occur when the workbook is password-protected. There are some workarounds to remove this protection but most of the examples you'll find online are outdated. Either way, the simple solution is to unprotect the workbook manually, otherwise use something like OpenXML to remove the protection programmatically.

Instead of OleDb, you could use the Excel Interop and open the worksheet as read-only.

https://msdn.microsoft.com/en-us/library/microsoft.office.interop.excel.workbooks.open(v=office.15).aspx

I had this same issue(Using the ACE.OLEDB) and what resolved it for me was this link:

http://support.microsoft.com/kb/2459087

The gist of it is that installing multiple office versions and various office sdk's, assemblies, etc. had led to the ACEOleDB.dll reference in the registry pointing to the OFFICE12 folder instead of OFFICE14 in

C:\Program Files\Common Files\Microsoft Shared\OFFICE14\ACEOLEDB.DLL

From the link:

Alternatively, you can modify the registry key changing the dll path to match that of your Access version.

Access 2007 should use OFFICE12, Access 2010 - OFFICE14 and Access 2013 - OFFICE15

(OS: 64bit Office: 64bit) or (OS: 32bit Office: 32bit)

Key: HKCR\CLSID{3BE786A0-0366-4F5C-9434-25CF162E475E}\InprocServer32\

Value Name: (Default)

Value Data: C:\Program Files\Common Files\Microsoft Shared\OFFICE14\ACEOLEDB.DLL

(OS: 64bit Office: 32bit)

Key: HKCR\Wow6432Node\CLSID{3BE786A0-0366-4F5C-9434-25CF162E475E}\InprocServer32\

Value Name: (Default)

Value Data: C:\Program Files (x86)\Common Files\Microsoft Shared\OFFICE14\ACEOLEDB.DLL

If the file is read-only, just remove it and it should work again.

I know this is a very old post, but I can give my contribution too, on how I managed to resolve this issue.

I also use "Microsoft.ACE.OLEDB.12.0" as a Provider. When my code tried to read the XLSX file, it received the error "External table is not in the expected format." However, when I kept the file open in Excel and then the code tried to read it ... it worked.

SOLUTION: I use Office 365 with company documents and in my case, the solution was very simple, I just needed to disable the sensitivity of the document, setting it to "public". Detail: Even after saving as "public" the green check still remained marked in "Internal Use", but the problem remained solved after that.

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.

ACE has Superceded JET

Ace Supports all Previous versions of Office

This Code works well!

        OleDbConnection MyConnection;
        DataSet DtSet;
        OleDbDataAdapter MyCommand;
        
        MyConnection = new System.Data.OleDb.OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=..\\Book.xlsx;Extended Properties=Excel 12.0;");
        MyCommand = new System.Data.OleDb.OleDbDataAdapter("select * from [Sheet1$]", MyConnection);
        DtSet = new System.Data.DataSet();
        
        MyCommand.Fill(DtSet);
        dataGridView1.DataSource = DtSet.Tables[0];
        MyConnection.Close();

(I have too low reputation to comment, but this is comment on JoshCaba's entry, using the Ace-engine instead of Jet for Excel 2007)

If you don't have Ace installed/registered on your machine, you can get it at: https://www.microsoft.com/en-US/download/details.aspx?id=13255

It applies for Excel 2010 as well.