Microsoft.ACE.OLEDB.12.0 provider is not registered

Question

I have a Visual Studio 2008 solution with two projects (a Word-Template project and a VB.Net console application for testing). Both projects reference a database project which opens a connection to an MS-Access 2007 database file and have references to System.Data.OleDb. In the database project I have a function which retrieves a data table as follows

 private class AdminDatabase
   ' stores the connection string which is set in the New() method
   dim strAdminConnection as string

   public sub New()
   ...
   adminName = dlgopen.FileName
   conAdminDB = New OleDbConnection
   conAdminDB.ConnectionString = "Data Source='" + adminName + "';" + _
       "Provider=Microsoft.ACE.OLEDB.12.0"

   ' store the connection string in strAdminConnection
   strAdminConnection = conAdminDB.ConnectionString.ToString()
   My.Settings.SetUserOverride("AdminConnectionString", strAdminConnection)
   ...
   End Sub

   ' retrieves data from the database
   Public Function getDataTable(ByVal sqlStatement As String) As DataTable
        Dim ds As New DataSet
        Dim dt As New DataTable
        Dim da As New OleDbDataAdapter
        Dim localCon As New OleDbConnection


        localCon.ConnectionString = strAdminConnection

        Using localCon
            Dim command As OleDbCommand = localCon.CreateCommand()
            command.CommandText = sqlStatement
            localCon.Open()
            da.SelectCommand = command
            da.Fill(dt)
            getDataTable = dt
        End Using

    End Function
End Class

When I call this function from my Word 2007 Template project everything works fine; no errors. But when I run it from the console application it throws the following exception

ex = {"The 'Microsoft.ACE.OLEDB.12.0' provider is not registered on the local machine."}

Both projects have the same reference and the console application did work when I first wrote it (a while ago) but now it has stopped work. I must be missing something but I don't know what. Any ideas?

Answer 1

Basically, if you're on a 64-bit machine, IIS 7 is not (by default) serving 32-bit apps, which the database engine operates on. So here is exactly what you do:

1) ensure that the 2007 database engine is installed, this can be downloaded at: http://www.microsoft.com/downloads/details.aspx?FamilyID=7554F536-8C28-4598-9B72-EF94E038C891&displaylang=en

2) open IIS7 manager, and open the Application Pools area. On the right sidebar, you will see an option that says "Set application pool defaults". Click it, and a window will pop up with the options.

3) the second field down, which says 'Enable 32-bit applications' is probably set to FALSE by default. Simply click where it says 'false' to change it to 'true'.

4) Restart your app pool (you can do this by hitting RECYCLE instead of STOP then START, which will also work).

5) done, and your error message will go away.