BUG: AV Running VB-Built Component in Multi-Threaded Environment

When running an apartment model ActiveX DLL that is created in Visual Basic in a multithreaded environment such as Microsoft Internet Information Server (IIS) or Microsoft Transaction Server (MTS), COM+, Internet Explorer, ActiveX EXEs, and so on, the DLL fails periodically with an access violation (AV).

The following steps may be used to change the DLL to avoid the problem. This may not resolve the issue in all cases.

Step-by-Step Example

1. Add a class module to the project.
2. Set the name of the class to clsEmpty.
3. Set the Instancing property of the class to 2-PublicNotCreatable.
4. In Project Properties, set the Start Up Object to Sub Main.
5. Add a BAS module, or put the following in an existing BAS module in the project:

         Public gEmpty As clsEmpty
         Public Sub main()
            Set gEmpty = New clsEmpty
         End Sub
   
   					

6. Save the project and recompile.

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

For additional information on errors when using an ActiveX DLL created in Visual Basic 5.0 that contains a For... Each loop that iterates through a Visual Basic collection, click the article number below to view the article in the Microsoft Knowledge Base: For additional information on threading issues with DLLs created in Visual Basic 6.0, click the article number below to view the article in the Microsoft Knowledge Base: