This past couple of week I’ve been contacted by a couple of developers concerned with Microsoft’s decision to stop supporting the Visual Basic 6.0 IDE, but to continue support for the Visual Basic runtime and some support libraries in Windows 7 and 2008. This made me think about revisiting the topic with new information and changes since February, when I wrote this post.

It is obvious that Microsoft has been trying to drop support for VB6.0 for a while now. They have extended it a couple of times, and they say they are committed to "make sure the IDE works" for the lifetime of Vista and Windows 2K8. But here is an important part of the support statement that is worth highlighting:

“VB6 runtime will ship and will be supported in Windows 7 for the lifetime of the OS.  Developers can think of the support story for Vista being the same as it is for Windows 7.  However there are no plans to include VB6 runtime in future versions of Windows beyond Windows 7.”

This means that the next version of Windows will very likely not include the VB6.0 runtime files. This has obvious implications if you have a  large application that will require several person-years of effort to migrate (or rewrite, if you decide to go that path). There are also some additional implications on the components you are using, since they may have a dependency on the VB6.0 runtime and thus may not work, even if the rest of you application is already in .NET and using these components through COM Interoperability. Just to be sure I’m not spreading unnecessary panic, Windows 7 is not even out yet, and it will be covered by Microsoft’s OS support policies, so you are good for at least the next five years. If you think the effort to move away from this platform will take longer than (or at least close to) this timeframe, make sure you start evaluation your options soon.

Another important thing to keep in mind is that the VB6.0 runtime files are 32-bit only. Starting with Windows Server 2008 R2, 32-bit mode (WOW64) is optional, and the next version of Windows Server (tentatively due in 2011-2012) will be 64-bit only. This affects both server-side components, ASP, and client-side applications running on the server through Terminal Services, Citrix, or any other remote access technology (though they may able to run using WOW64, albeit requiring an extra configuration step).

A big change since I wrote the last post is that now Windows 7 includes a complete XP virtual machine to run legacy apps, known as XP Mode. I already made a couple of posts on this, and basically, this seems to be a good intermediate steps to “buy some time” before companies move their applications to supported platforms.

As I recommended in the previous post, you should read the  "Support Statement for Visual Basic 6.0 on Windows Vista, Windows Server 2008 and Windows 7". Also, the Microsoft Product Lifecycle details the specific dates when support ended for VB6.0.