@h2oyesss The normal way to do that is CurrentProject.Connection. You don't need to manually specify the string. –
This make me wonder that If I use currentproject.connection , It may work. and really. currentproject.connection use OLE DB 12
Private Sub test1()
Dim rs As New ADODB.Recordset
Dim size As LongLong
rs.Open "Select * From LocalFiles ", _
CurrentProject.Connection, adOpenKeyset, adLockOptimistic
rs.AddNew
size = 12345678912345#
rs("FileSize") = size
rs.Update
rs.Close
End Sub