You receive an "Unrecognized database format" error message when you open a database created with Access 2000

When opening a database created with Access 2000 through MFC DAO classes in Visual C++, you get the following error message: You also get this message when trying to create a new MFC DAO database SDI or MDI project using MFC AppWizard.

This error message occurs because the MFC DAO classes that ship with Visual C++ 6.0 load DAO 3.5 (Dao350.dll) by default. DAO 3.5 uses Jet 3.5, which can only open Jet 3.5 format (or earlier) databases. Access 2000 creates Jet 4.0 format database files, which are unrecognizable to Jet 3.5. To successfully open an Access 2000 database using the MFC DAO classes, you need to use DAO 3.6 (Dao360.dll). DAO 3.6 uses Jet 4.0, which can open any available Access database format.

Currently, there is no workaround to using AppWizard with Access 2000 data sources.

For your application to use version 3.6 of DAO, you must update the version of MFC at run time to MFC version 6.01. To do this depends on whether you are building the application to use the MFC DLL or to build with the static libraries for MFC.

If you are linking with the MFC DLL, you can specify that you want MFC to use DAO 3.6 by inserting the following line of code before you open an Access 2000 database: Insert this line in the CYourApp::Initinstance() function of your program. If you are building with the static MFC libraries, following are the steps to get static builds of MFC to use DAO 3.6:

1. Modify the Daocore.cpp file in the MFC SRC directory. You will receive the following comment:

   // Determine whether to use DAO 3.6, 3.5, or 3.0
   // Use DAO 3.0 if DLL build and not built with MFC 4.21 or later
   // Use DAO 3.6 if MFC 6.01 or later
   // otherwise, DAO 3.5
   						

   Add the following lines:

   #undef _MFC_VER
   #define _MFC_VER 0x0601
   						

2. Rebuild the library for the variant you need. For example, to build the static MFC library, debug version, non-Unicode, with no browser files use the following command at the command prompt in the MFC\SRC folder:

     nmake DEBUG=1
   
   for release:
      nmake DEBUG=0
   
   for unicode builds:
      nmake DEBUG=1  UNICODE=1
      nmake DEBUG=0  UNICODE=1
   						

Note You need to make certain that the compiler tools are in your path. If not, you may need to run the Vcvars32.bat file located in the Visual C++ \BIN folder. Also note that when you build these new versions of the libraries, they will be copied over the top of the existing ones in the MFC\LIB folder so you may want to save the old ones first.

This behavior is by design.