FIX: MFC DAO or ODBC App Crashes on Exit

• Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.1, 4.2

SYMPTOMS

An application intermittently crashes on exit and an error similar to the following appears:

<application> caused an invalid page fault in
module KERNEL32.DLL at 0137:bff9a07c.

RESOLUTION

Call the LoadLibrary() function on the Jet Engine as shown in the sample code below. This call needs to be done only once during execution of the program. To minimize any adverse affect on performance, call LoadLibrary() only after the database has been opened. Do not call FreeLibrary() for this DLL. The DLL will be automatically unloaded when the application exits.

This bug has been fixed in Jet 3.5 that is included with Visual C++ 5.0. If you are using the ODBC, you can simply use the newer ODBC driver that is available with Visual C++ 5.0. If you are using DAO, you need to build your application using Visual C++ 5.0 to use DAO 3.5. The earlier MFC classes use DAO/Jet 3.0 and do not recognize DAO 3.5.

STATUS

This bug has been fixed in Jet 3.5 that is included with Visual C++ 5.0.

MORE INFORMATION

This problem occurs only if a dialog resource is loaded. This includes applications that use CFormView-derived classes, such as CRecordView and CDaoRecordView, as well as dialog-based applications.

The following sample code shows the workaround for a default MFC AppWizard application using the MFC DAO classes. The call to LoadLibrary() is added to the Open() function of the CDaoRecordset-derived class named CMySet. Similar logic can be used for the MFC ODBC classes.

To fix the DAOEnrol sample, add the LoadLibrary() call in the sample code below to the CDaoEnrolDoc::OnNewDocument() function, before the call to the base class CDocument::OnNewDocument() function.

To fix the Enroll tutorial, add the LoadLibrary() call in the sample code below to the CEnrollDoc::GetDatabase() function, after the call to m_database.Open().

Sample Code

   void CMySet::Open(int nOpenType, LPCTSTR lpszSql, int nOptions)
   {
       CDaoRecordset::Open(nOpenType, lpszSql, nOptions);

       // Load the Jet Engine to ensure that it remains in memory
       // during the shutdown process.
       LoadLibrary( "MSJT3032.DLL" );
   } 

Keywords : kbinterop kbprg kbDAO kbDatabase kbMFC kbODBC kbVC kbVC500fix
Version : WINDOWS NT:4.0,4.1,4.2
Platform : NT Win95 WINDOWS
Issue type : kbprb