Applications Referencing the ADOX Library Fail Under Windows Vista

Provided by: Luke Chung, FMS President

Your existing Visual Studio .NET or Visual Basic executable, or compiled Access application (MDE or ADE) is running fine on Windows XP. However, when your users upgrades to Vista, it no longer works -- or portions of it fail. Why?

After considerable head-banging, we discovered one cause of this is due to a compatibility problem with the ADOX library in Windows XP vs. Vista. (There may be other reasons, but this is what we found so far).

The ADOX Library is the Microsoft ADO Ext. 2.7 for DDL and Security. You can specify it under the library references for your project:

In Windows XP, the version is between 2.5 and 2.8. If you use the oldest version, it automatically adjusts if the user's machine has a later one.

In Windows Vista, ADOX version 6.0 is available. Unfortunately, the .NET/VB/Access executable does not automatically upgrade to this version. However, it does not completely break either -- the IsBroken property of the reference is False. Nonetheless, indications of a broken reference appear. For instance, in Access, queries that use VBA functions no longer work.

Workarounds

There are two ways to work around this problem, neither of which are ideal:

Late Binding

Rather than referencing ADOX as a library, reference it as an object in your code when it runs. Of course, this is less efficient and prone to errors since the compile time checking and Intellisense are lost.

Create Separate XP and Vista Builds

Create your executable in Vista with the new version of ADOX, and give that version of your program to people running Vista. That version won't run on Windows XP, so you'll need to maintain a separate build for that and install accordingly. Of course, this doesn't work when an existing machine is upgraded to Vista.

Of course, neither of these options work if you don't have the source code. Even if you did, creating a new build is prone to all sorts of other errors related to having the other library dependencies correct, the proper ActiveX controls installed, and the standard challenges of dealing with DLL hell for a legacy application.

Hopefully, the folks at Microsoft will provide a patch soon to address this failure of backward compatibility, so we don't have to change our executables. In the meantime, stick with Windows XP for these applications. Good luck!

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