PRB: Must Open MDB on Read-Only Media with adShareDenyWrite

ID: Q195475

The information in this article applies to:


Opening the connection on a read-only Microsoft Access Database (.mdb file on a CD-ROM, a floppy disk that is write protected, or a hard disk that is read-only to the user, and so forth) with the following code causes an error to occur. The following code opens a connection on a Microsoft Access database file on a CD-ROM:

   Dim con as new ADODB.Connection
   con.Provider = "Microsoft.Jet.Oledb.3.51"
   con.Open "Data Source=E:\testdb.mdb"

It causes the following error:

   The Microsoft Jet database engine cannot open the file E:\testdb.mdb.
   It is already opened exclusively by another user, or you need
   permission to view its data.


The Jet OLEDB provider opens databases, by default, in Read/Write mode. Jet requires the creation of a locking file (.ldb file) in order to open a database file in shared access mode. If you request shared access mode, Jet attempts to create the locking file, which fails on read-only media. If you open a database using exclusive mode, Jet does not need to create the locking file.


Open the database in read-only and exclusive mode. You can do this by setting the Mode property of the connection object to adShareDenyWrite.

The following code opens a connection on a read-only Microsoft Access database:

   Dim con as new ADODB.Connection
   con.Provider = "Microsoft.Jet.Oledb.3.51"
   con.Mode = adShareDenyWrite
   con.Open "Data Source=E:\testdb.mdb"


The following Microsoft Knowledge Base article describes the same problem and a resolution when using Data Access Object (DAO):

   ARTICLE-ID: Q191737
   TITLE     : PRB: DAO MDB on Read-Only Media Must Be Opened Exclusively

Microsoft Developer Network Library, Visual Studio 6.0; search on: "Microsoft Data Access SDK"

Additional query words:

Keywords          : kbADO200 kbDatabase kbJET kbMDAC kbODBC kbSweepNext 
Version           : WINDOWS:2.0,3.51
Platform          : WINDOWS
Issue type        : kbprb

Last Reviewed: November 13, 1998