Can we use .Net 4.0 framework in the Visual Basic Interop form?

Question

I'm having a project which is to add new features to a VB6 application. In order to migrate the application to the more advanced technology incrementally, we choose to use VB Interop technology. However, we found that the VB Interop Form is actually based on .Net 2.0. So, I'm asking how can we use higher version of the .Net framework?

thanks

Answer 1

Short answer is no, but stable in 3.5 framework. Microsoft is aware of the issue, but can't tell you when there would be a fix. You can find more here.

Another good read here.

Answer 2

Interop Forms Toolkit can be used with .NET 4.0. I have been using it for more than 6 months with no problems.

The problem discussed here is due to In-Process Side-by-Side Execution, introduced in .NET 4. With this you can have different versions of the CLR running in your application. This can be fixed by using an app.config file:

<?xml version="1.0"?>
<configuration>
    <startup useLegacyV2RuntimeActivationPolicy="true">
        <supportedRuntime version="v4.0"/>
    </startup>
</configuration>

I answered a similar problem here, and here