Related
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);
}
"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;";
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;"""
(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.
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.
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
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
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.
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.
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.
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"";"
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();
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.
the file might be locked by another process, you need to copy it then load it as it says in this post
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
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.
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.
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
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.
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.
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 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.
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).
I've had this occur on a IIS website that I host, rarely but periodically this error will popup for files that I've previously parsed just fine. Simply restarting the applicable app pool seems to resolve the issue. Not quite sure why though...
This happened to us just recently. A customer of ours was getting this error when trying to upload their excel file on our website. I could open the xlsx file fine on ms excel and don't see any irregularities with the file. I've tried all mentioned solutions in here and none worked. And i found this link Treating data as text using Microsoft.ACE.OLEDB.12.0. What worked for our case is adding IMEX=1 attribute to the connection string. So if you are using Microsoft ACE OLEDB 12.0 this might help fix your issue. Hope this helps.
<add name="ExcelTextConnection" connectionString="Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties='Excel 12.0;HDR={1};IMEX=1'" />
Hi I am trying to get all history url of mozilla firefox. To do that I am accessing places.sqlite file inside %appdata%mozilla/firefox/profile/*.default folder. I am using system.data.sqlite dll in my code and tried x64 and x86 both of the solution. As I am trying to connect the database it is showing me an exception that the file is encrypted or not a database file.
To cross check this exception I've installed a dbmanager for sqlite and opened it. This is showing me all the data that I want to show. But I am not able to get the same data using c# application. Please Help me to get this thing resolved.
SQLiteConnection sqlite_connection = new SQLiteConnection("Data Source=" + dbPath + ";Version=3;New=True;Compress=True;Integrated Security=SSPI;");
SQLiteCommand sqlite_command = sqlite_connection.CreateCommand();
sqlite_connection.Open();// exception occurs here
I've this code :
OracleConnection con = new OracleConnection("data source=localhost;user id=fastecit;password=fastecit");
con.Open(); string sql="Select userId from tblusers";
OracleCommand cmd = new OracleCommand(sql, con);
OracleDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{ messageBox.Show(dr[0].Tostring()); }
Same code in both projects,
in project1 "WinForm" Is Working correctly
in project2 "Excel 2007 addins" Following error appears:
ORA-12154: TNS:could not resolve the connect identifier specified
I'm using C#.net 2010 ,office 2007 , windows8, oracle 10g.
When preparing a manual connection to the database, as shown in the picture
Visual Studio, open View menu + Server Explorer.
Right mouse click on Data Connection + Add Connection + Select Oracle Database
server Name : localhost or name of my machine, set username & password and click on Test Connection, test is no succeeds.
ORA-12154: TNS:could not resolve the connect identifier specified?
In case the TNS is not defined you can also try this one:
If you are using C#.net 2010 or other version of VS and oracle 10g express edition or lower version, and you make a connection string like this:
static string constr = #"Data Source=(DESCRIPTION=
(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=yourhostname )(PORT=1521)))
(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=XE)));
User Id=system ;Password=yourpasswrd";
After that you get error message ORA-12154: TNS:could not resolve the connect identifier specified then first you have to do restart your system and run your project.
And if Your windows is 64 bit then you need to install oracle 11g 32 bit and if you installed 11g 64 bit then you need to Install Oracle 11g Oracle Data Access Components (ODAC) with Oracle Developer Tools for Visual Studio version 11.2.0.1.2 or later from OTN and check it in Oracle Universal Installer
Please be sure that the following are checked:
Oracle Data Provider for .NET 2.0
Oracle Providers for ASP.NET
Oracle Developer Tools for Visual Studio
Oracle Instant Client
And then restart your Visual Studio and then run your project ....
NOTE:- SYSTEM RESTART IS necessary TO SOLVE THIS TYPES OF ERROR.......
The database must have a name (example DB1), try this one:
OracleConnection con = new OracleConnection("data source=DB1;user id=fastecit;password=fastecit");
In case the TNS is not defined you can also try this one:
OracleConnection con = new OracleConnection("Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=DB1)));
User Id=fastecit;Password=fastecit");
run the below command in command prompt
tnsping Datasource
This should give a response like below
C:>tnsping *******
TNS Ping Utility for *** Windows: Version *** - Production on *****
Copyright (c) 1997, 2014, Oracle. All rights reserved.
Used parameter files:
c:\oracle*****
Used **** to resolve the alias
Attempting to contact (description=(address_list=(address=(protocol=tcp)(host=)(port=)))(connect_data=(server=)(service_name=)(failover_mode=(type=)(method=)(retries=)(delay=))))**
OK (**** msec)
Add the text 'Datasource=' in beginning and credentials at the end.
the final string should be
Data Source=(description=(address_list=(address=(protocol=tcp)(host=)(port=)))(connect_data=(server=)(service_name=)(failover_mode=(type=)(method=)(retries=)(delay=))));User Id=;Password=;**
Use this as the connection string to connect to oracle db.
Creating a form application in vs 2012. I have office 2013 installed, win 8 64 bit. I get the above error for the below piece of code.
public void SetConnection(string text1, string text2, string text3, string text4, string text5, string text6, string text7)
{
connectionString1 = "Initial Catalog=test; Data Source=work\\sqlexpress";
connectionString = "Data Source='c:\\Users\\test1.xlsx';Extended Properties=Excel 12.0 Xml;Readonly=False;";
database = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;" + connectionString);
database.Open();
database1 = new OleDbConnection("Provider=SQLOLEDB.1;" + connectionString1);
database1.Open();
}
I tried using jet drivers but would not work, so i turned to ace. First i got "Cannot find installable ISAM"; so installed AccessDatabaseEngine_x64 which leads me to this error. I then changed my build to x86 and same errors. So i'm out of options. I did try previous versions of AccessDatabaseEngine from 2007 and 2010 but no luck, any suggestions.
database = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source='c:\\Users\\test.xls';Extended Properties= \"Excel 8.0;HDR=Yes;IMEX=1\";");
The above connection string works using jet although i have to leave the excel file open for the time being as i get "could not decrypt file" error otherwise. I also had to save the file as a 97-03 excel xls file.
string connectionString = "Provider=Microsoft.Jet.OleDb.4.0;Extended Properties=Excel 12.0 Xml;HDR=YES; Data Source=C:\Users\q\Desktop\Ug\Test.xlsx";
As said here, probably you have the 64-bit office installed which doesn't have the 32-bit compnents installed (links are provided there). You may also have to biuld your project targetint x86 platform.
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);
}
"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;";
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;"""
(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.
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.
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
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
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.
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.
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.
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"";"
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();
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.
the file might be locked by another process, you need to copy it then load it as it says in this post
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
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.
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.
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
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.
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.
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 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.
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).
I've had this occur on a IIS website that I host, rarely but periodically this error will popup for files that I've previously parsed just fine. Simply restarting the applicable app pool seems to resolve the issue. Not quite sure why though...
This happened to us just recently. A customer of ours was getting this error when trying to upload their excel file on our website. I could open the xlsx file fine on ms excel and don't see any irregularities with the file. I've tried all mentioned solutions in here and none worked. And i found this link Treating data as text using Microsoft.ACE.OLEDB.12.0. What worked for our case is adding IMEX=1 attribute to the connection string. So if you are using Microsoft ACE OLEDB 12.0 this might help fix your issue. Hope this helps.
<add name="ExcelTextConnection" connectionString="Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties='Excel 12.0;HDR={1};IMEX=1'" />